many teenagers feel the same as you even those in main stream education, you are at an age when hormones and emotions are running on overdrive and it is extra hard in a small group especially with so many differing conditions in the mix. this situation will not last forever, once school is over everyone goes their seperate ways. very few friendships last as lives take on new commitments and responsibilities and with those will come new friends
in the meantime, health issues may prevent you doing some clubs, but you may still be able to do others. depending on what your health issues are you may be able to find some specially for others with similar issues or a youth club or a sport that you enjoy, swimming is great for most people and if you talk to the group/club leaders first about your health issues they may be able to find ways that you can join in as much as is possible. I love art, but can't draw, so the group leader put together bits so i can interpret the thing they are drawing in a collage, often my finished picture is nothing like the subject, but i have fun and meet others - it's one night i dont spend alone at home!
Although i am unsure about all religions, church does seem to be the place to meet people, they are most likely to accept you as you, not judge by health issues. there may be a youth club or choir or something that you could give a try. remember although having friends of your own age is good, having friends who respect you for just being you is better and age becomes less important as you get older.
till then you always have friends on here to talk to x