Trying to find and keep a job but i just keep getting fired

So firstly I want to say that I have social anxiety, depression,an eating disorder, IBS and 5 vitamin deficiencies (I get injections every month and take many tablets everyday). My boyfriend and I rent our own place and he is self employed, I’m very lucky that his business is doing well and we are able to pay our bills but don’t have much money to spare.

I’ve been working for him, just doing his books and drawing things up for him for the past couple months but he’s pushing me to get a full time job somewhere. I know that it would be better for us if I did because then we would be able to start saving to buy a house but whenever I get a new job I end up having a panic attack and get really ill (IBS or vitamin deficiency flares up), I’ve pushed myself so many times to just carry but I will end up being physically or mental ill.

I’ve spoken to him about just getting a part time job at the moment to build myself up but I have a couple problems...

-I don’t know what I want to do.

-I hate just sitting at a desk.

-My IBS, eating disorder and vitamin deficiencies have made me so weak that I can’t do physical work.

-My social anxiety makes it so that I can’t travel very far otherwise I freak out and I live in a tiny village that’s in the middle of nowhere.

I’m really struggling to think of what I can do and it makes me feel completely useless, I’m 22 and my boyfriend is 31, he’s wanting to settle down and have his life sorted but I feel like I’m holding him back. So many times I have thought that we’d both be better off if I moved back to my mum’s and let him have the life he wants with someone that’s better and doesn’t have these problems. He tells me all the time that I’m the person he wants to be with and that no matter what, he will never leave me.

I just don’t know what to do, any advise?