Go to Lens Crafters or Vision Works or any vision place to get your eyes examined, they will give you a prescription letter with your name and number. Make a copy of that and send it with your application.
Whomever you are living with, tell them to make an affidavit attesting that you have been living with them for x amount of time. Or you could go to a lawyer, they know what to do in this type of scenarios.
How long have you been in the States? Have you never been to the doctor?
Your I-94 will prove that you been in the United States but you need one more evidence for your residence here in certain location.