Disability?

My 4 yr old daughter has a speech impediment, gross motor and fine motor skills delays. She goes to a special learning center half days 4 times a week. Where she sees a speech therapist, Physical Therapist, and an Occupational therapist. The physical Therapist Has suggested that My daughter get Orthopedic Shoe inserts with small bres because she has Val Gus knees and flat feet. Other then these things She has severer seasonal asthma. I attend College, I’m a single mom I work 2 jobs, and money is tight. But the state child support prosecuting attorney recommended that I try to get My daughter on SS disability. She says if I apply and don’t get it then I can get an attorney that will only charge me if he wins even then he only takes a one time portion of the disability. So I have nothing to loose and she gave me a name of an attorney friend of hers who deals with SS. I called the SS office and they made an appointment with me for an interview plus sent me out paper work in the mail. She told me to bring my daughter’s birth certificate, my license, a copy of her IEP, and a note from her doctor saying that she has read the IEP and she is aware of my daughter’s disability. I’m not worried about getting any of this information. I was thinking of taking a copy of a court case granting me full legal and physical Custody of her would also be a good idea. Is there anyone else out there who has applied for SS disability for their child? What do you think the chases are of getting this benefit for her?