Sassyfras,
In some way they may not be able to care in the way you wish they could. Don't beat yourself up about it. Maybe lower your expectations of what you will get from them and remind yourself of the simple things they have done for you - a place to live for now. Maybe not perfect, but...
Also, if you can, just give them the short simple facts when you are feeling up to it. "This helps me with my sypmtoms for now", period. Don't know how they react to your crying in front of them, but if it would help them see where you are at you could try letting it go sometime. I find when I cry, I am at my most honest and other people see that. Don't know how it is in your family though, you would know what was safe.
Would they consider going to therapy with you at least once, just for the info?
They may think you are going to get over this right away and all will soon be fine. They are on their learning curve too - they just don't know it yet:).
Take care, can you get yourself some more supplements?