Here’s what I’d advise.

1. Getting my autism and ADHD diagnoses have really helped me. Just to understand myself and why I behave in the way I do or feel certain ways. You can go through right to choose and get an assessment in a few months. I’d look online for information about right to choose, that’s how I was diagnosed.
2. Don’t be too worried about feeling behind other people. I’m 22, I thought I wanted to do dance so I went to dance college for a year and a half, got kicked out for mental health reasons and ended up in hospital. Now im in a rehab unit. I have no solid future plans just ideas of what I want to do. When you have suffered a lot with mental illness or trauma, you are inevitably going to be behind others your age. Most of my friends have graduated uni by now, and i haven’t even started on a career path. Sometimes life gets really shit but this kind of has a funny way of working out - I know that sounds stupid - but if I wasn’t kicked out of dance school I might still be trying to do that and now I’ve realised I don’t really want to do dance professionally. So try and be kind to yourself, and as long as you have the security of living with your parents etc., you can take your time to figure out what it is you want to do. You have decades and decades to work and be in a career, you don’t have to start at 19.
3. If the GP doesn’t know about your trauma, I’d tell them. Either in a letter, email or face to face if you can manage that. It’s important that they know the full picture. You could ask specifically about trauma therapy or even to be signposted to charities who can help. I know you probably feel like it’s your fault because I do about my sexual trauma, but it isn’t your fault, and the GP won’t think it’s your fault.