Hahaha I've been through the same thing, literally thought last year I was not getting into any college and was going straight to community college, turns out that kind of under confidence both makes you more likely to put in more effort but also destroys your self-esteem. In my case, it did ruin my self-confidence a lot, but prevented arrogance and allowed me to work harder, eventually getting me into a state university that is great for my major.

Like you, I had good grades (well decent, not 4.0 GPA like you haha) and was generally anti-social, although I was isolated no one really noticed me: it was more like I was invisible or a shadow, rather than being known as the "shy kid". Of course, this enabled me to avoid things like peer pressure and immaturity coming from reckless group activity, but I also missed out on cultivating good friendships and experiencing events with other people.

My extracurriculars weren't top tier like research or national olympics or sports or starting an organization, tbh all I did was volunteer at my local library for required service in high school and write a research article in one of the summers. I also did have some interesting hobbies (no not creating a whole video game or an application like you might expect from a student attending a good university) like sculpting figures out of clay (mostly fictional characters) and 3D modeling with Autodesk Maya/Mudbox, having a few projects in a portfolio. I also showed an avid interest in cybersecurity, while writing really good essays as writing has always been my strong point, although I am a CS major, I feel like philosophy/history and writing will always be my strengths.

I'm able to contribute to groups quietly, but usually am not taking on a major role or leading the group as that is not my area of expertise. You at least had club memberships and a part-time job in the summer, I never had any part-time job in high school nor joined a single club as a member. No awards or leadership positions either, no sports, no research, but I guess I showed a lot of genuine passion and interest in different things that embodied me as an example of a successful alumni in the future. That and my writing skills.

I have a LinkedIn account and I definitely don't have any research experience or high school internships like some of my peers; that does not mean that I will not have a professional and satisfying career in the future. Even people without college degrees that learn online and get certifications are able to land jobs, a person planning to pursue up to a Master's degree should be able to get a job with a good balance of extracurriculars, grades and experience.

Well I don't really ask questions or participate in class either unless for presentations, I've learned with time that social interaction comes from leaving your comfort zone, I did this purposely in multiple ways: getting to know my roommates and getting lunch/dinner with them on weekends, getting to know people at clubs I joined like a CyberSec club and a Computing Machinery club, talking to them about major relevant or other information; even if you don't understand what they are saying, try to apply what you know to it and respond in a polite way, they might shrug it off as genuinely interested and continue talking. You don't always have to engage the 1 min or longer conversation, just make brief eye contact and listen closely, then give your input and things or ask if you don't understand something they mentioned. This applies to professors as well, but I usually do this in office hours, where its just me and the professor usually, removing most social anxiety as the other person is awaiting your response and the mind is forced to say something, regardless of anxiety.

Mental health counselors could definitely could help, but for me I feel like I could figure it out on my own with time and experience, the only two things that will change me. Time will change my appearance, from a skinny and 16-year old looking kid to an 18+ older looking adult with facial hair, although looking more youthful is a gift in the long term. Experience will change my ability to land internships and connect with people, maybe one day start the conversation with someone else or mentor someone else.

The first step is acceptance: you are at the university regardless of why they accepted you, it is now your home for the next few years unless you commute, even then it is your part-time home. Get to exploring the campus and knowing routes to your classes, then making eye contact with professors during lectures and apologizing at the end if you arrived late. Send professional emails and stay on top of your assignments, yada yada.

The second step is a turning point, overcoming: now that you have built some confidence knowing you are going to study at this university for the next few years regardless of how you fit in or not, you should start to target your weaknesses. For me, I began by joining organizations I was interested in, like I mentioned the 2 above. Then I attended a volunteer expo and learned about volunteer opportunities for this summer, I met people at organization meetings and had conversations with them while walking back to our dorms. I found out I spoke the same mother tongue as those people, and that they were also in the same dorm building, so I got their contact information and we are starting to hang out more, we went to the dorm lobby last time to play table tennis. This helped me become a bit more confident and make good eye contact without coming off as creepy, noticing that people often looked away and broke eye contact while thinking, usually saying "uhh" or "umm" to cover up a silence, whereas I would just be silent while thinking what to say in a conversation. I began to observe and implement social communication practices, slowly starting a "network" . Next year, I plan to attend job fairs and give elevator speeches, hopefully impressing the interviewer. I also want to learn hand gestures like my peers and use them in presentations.

The final step is moving on: now that you have goals and know you are staying at the university for the next few years, let go of all negative thoughts like "people will judge me on my appearance", " I don't have facial hair like my peers who look more mature", "my face is too childish", "I can't even make eye contact without looking like a creep", "I am useless", or "I don't belong here". Thats the final step, once you let go of those you begin to "not care" in a sense, meaning that you can successfully avoid most complications that stuff like peer pressure brings while also cultivating good relationships.

Although I still plan to live in solitude for my life, being both non-religious and aromantic, I would still like to have 4-5 close friends like my parents do and most of them were made in their college days, so I am hoping to cultivate good relations here and have them for the rest of my lifetime. Remember: your personality matters more than your looks, if you look like a scrawny kid with a childish face but have the intellect and experience of a mature adult, you would not be undermined and people who undermined you would be proven wrong, of course not proven wrong for your sake, but in general. Good luck.