How do I meet new friends?

My whole life I’ve never had a huge amount of friends. I’ve only ever had a maximum of 8 close friends.
I started secondary/high school in 2013 and I only had one friend at the time. We then “broke up” in 2015 and I became friends with 8 people and they were really close to me and visa versa. In 2018 I did my GCSE’s and after leaving school my friends went to college whilst I was doing my own thing.
At that same time my health started to get to it’s worst point as I have severe anxiety disorder, Autism and Chronic Fatigue Syndrome, and because of that I couldn’t contact them in any way as I was really unwell but I also knew that they were in college and I didn’t know their schedules.
I didn’t end up seeing my friends in person until October just this year so it had been almost a year and a half since I last saw them. When I saw them last, there were only 4 of us as the other 5 were busy doing college assignments etc, and with the three friends I was with, they didn’t really seem to care about me and they were more focussed on their phones or talking about their college courses which made me feel really miserable.
Since October my friends haven’t bothered to contact me whatsoever and I haven’t bothered contacting them either as for years now I have always been the one to start a conversation and I’ve just got fed up with having to always start conversations.
Today, I went on social media like I normally do and noticed that my friends had met up for the 10th time this year (if not more times this year) and like normal they haven’t bothered to ask me if I wanted to meet up with them or not, which to me is quite upsetting knowing that people who I have been really close to for the past few years aren’t bothering with me anymore and I don’t know why.
It’s gotten to a point now where I’ve just had enough with these people and I’m wanting to meet new people and make new friends.
If anyone reading this knows how I could meet anyone please could you give me any suggestions on how to meet people.

A bit about me to help just in case:
I’m 17 years old, I’m from southern England, I can’t take part in any physical activities due to my CFS and I am Autistic (like I previously mentioned) so being surrounded by loads of people can be a bit too much for me. Also people have suggested to me to go to college however college isn’t something I want to do.