You should be incredibly proud of yourself!!!!!! I bet your Mum was astounded !!!! That is a really big step, and a fantastic step in the right direction after two long years.
You can buy those packs of microwaveable rice, Tilda do loads of different packets, from totally plain, mushroom, tomato, lemon rice to egg fried rice and ...well...they do loads. They are SO easy to do and you can't get it wrong (AND being microwaved means there can be no germs!) ALl you do is squish the packet around in your hands to separate the rice, then you tear a corner to let the steam escape and microwave for 2 minutes. It is steaming hot and perfectly cooked.
Later on, once you have broken through these barriers you can learn to cook rice (its easy , but yes you can over or under cook it, not that it will hurt you but it won't be as nice to eat!) but why not make it easy on yourself at first and just deal with the trying of a few bites of news things.
Same for cooking chicken, learn how to cook it later.....
I was suggesting buying a packet of chicken pieces already cooked and try them cold. Any supermarket, in the meat section (near the ham and other cooked meats) will have some absolutely plain chicken breast pieces already cooked and ready for sandwiches. You keep it in the fridge and tear a little piece off and try it, like the bite of toast you just had. It's already properly cooked and ready to eat. The only thing is, once the pack is opened you can only keep it for a few days (it will tell you on the packet). Be very careful, go very slowly, a tiny bit here and there.
You know what , your motivation to NOT be treated by someone else/other people seems strong enough that bit by bit you could make a big difference to your eating habits.
Can your Mum help you with choosing and getting some plain microwaveable rice and ready cooked chicken ?
---------- Post added at 22:17 ---------- Previous post was at 21:56 ----------
Edited to add......
If your Mum went to the doctor with you, she could help discuss you getting some therapy for your problem, and make sure that you are treated at home in the community?!