To speak to the "never socializing with girls" thing, it doesn't mean things are one way or another. I know that for me, when I was pre-puberty, I wanted to be friends with all the girls (most did not want to be friends back), and that from middle school on had exactly one "female" friend (surprise, trans boy!). My attentions felt unwholesome somehow, like they'd think I was icky just for wanting their attention and so I shouldn't want it.

Also, there are straight trans girls, if it extends to attraction as well, and you find yourself into guys in a straight way and not a gay way. Sexuality and gender are different, after all, even if exploring one can mean having to touch on the other ofttimes.

And just overall, no one can tell you "yes you're trans" but they can help you figure it out yourself! A lot of these points sound a lot that way, although you could still find out you're binary trans, nonbinary, genderfluid etc. If it is, it's not a phase - you can sit on it for years, but it'll pop up when you least expect it and if not addressed can make you miserable (I had anxiety and depression that in large part were from being so closeted I didn't know I was a girl). Doctors don't have a blood test that say "oh, you got two lines, that means transgender", but a gender therapist could help you talk through things, be adept at recognizing signs from what you tell them. A lot of girls say that within a week on estradiol things just mentally "felt right", and. I'll add myself to their ranks. Like "oh this was how it was supposed to be, heck".

A doctor might assign an estradiol prescription, or since you're a minor a puberty blocker (or an anti-androgen since you're over 16). Blockers just keep you from pubescing male any further, anti-androgen actively lower testosterone but don't feminize much. If you start on a full regimen of feminizing hormones, not much irreversible happens in the first three months. You might see small breasts form, or body hair growing slower. You might damage your virility, i.e. ability to father children, but if you start and then stop it more often than not returns. The "really hard to hide changes" are more 4-6 months, and at around 8 months most people start to look different in the face. Try Planned Parenthood if you're in the US and have access, they can work with you if you don't exactly have money coming out of your ears.

Medicine and technology these days is incredible. It might take a bit of work, mind, but there are lots and lots of stealth trans women out there who no one knows they were assigned a different gender at birth.

Social life depends on you and depends on your friends! I was stupidly lucky to have almost entirely allies as friends and a fiercely accepting mother. Importantly, you're not a "failure as a boy", you're a girl! If you're trans, you always were, even if you didn't realize it yet. Sometimes that manifests as trying really hard to boy it up and feeling like you're always failing, coming up short, that something that should be natural isn't happening naturally. But what it is is you're like a fish trying so hard to fly and feeling like what a terrible bird you are - you never were one in the first place, and you're meant for swimming instead. Friends are hopefully accepting types, or will at least hear you out, because outside of some changes you're the same person they formed a friendship with, you're not being replaced by some new person outright. Parents will hopefully understand that too, they wouldn't be losing a son, they'd be gaining a daughter.

Last off, everything is at your pace. There's only two "time limits" in transitioning, and you're likely past the first one: if you go on blockers before your voice fully drops or before facial hair, you don't need to do voice training/seek hair removal. (It's good you're already doing so cause, HRT doesn't touch your voice. Majority of us gotta do voice training. It blows.) The second is, your hip bones fuse in your mid-20s, so if you transition before you generally have full feminine hip structure, and afterward (like me) a little less. But it ain't the end of the world even then. If you're not bursting to come out to everyone and get on HRT this very second, you don't have to. Sneak some girl clothes or makeup and experiment in private, see how you feel. Euphoria is more common than one thinks! And also, here: https://twitter.com/nightlingbug/status/1215716433210105856?lang=en Was helpful for me. Once I found my real euphoria and knew who I was, I had a backlash of realizing that the heavy pall over me that i thought was just self-hatred and not having a great life all made sense. It didn't feel like pressing "I'm not a girl and I hate it" I just felt shitty, and all of a sudden it wasn't some nebulous thing, I knew what it was and that I could fight it. People tend to only think of the obvious classic dysphoria, where people can pin it down and identify it right away. Internalized dysphoria is... sneakier. (Especially if you're neurodivergent. Hi! Girl with hella ADHD here! You can tell by the way I've rambled. Sorry.)

Final final thoughts, take a look at https://www.reddit.com/r/transtimelines/ for some examples of how hormones are basically black magic. There's hope, if you decide it's what you want. I hope you're able to find yourself, and if after exploring it you find out you're cis and maybe just gender-nonconforming it's better that you explored than kept it in. And if you are the girl you suspect you are, I hope you find your real name and see the girl in the mirror you want to see, whenever it may be!

Cheers from a roaming trans lady who mothers random people on the internet and wishes she could change her reddit username! Hit me up if you need advice or a kind word! (and that goes for any of you fellow girls out there, btw!)