To clarify.... I agree with the other posts, the attorney will get paid from back pay if you are approved. I do not know how much, sorry.

I think it's great you will be seen by a dr soon! See what you can do to get through the day to day with your illnesses with help from a professional. Great first step! Also mention to them you are applying or considering applying and they may be able to help.
Any good attorney will request your records for your case, so it's best to tell them upfront how badly you are struggling.

Best wishes.