I will share my personal experience with you. I applied for SSDI myself and was approved. It was easy. But, FIRST, you must understand what disability means to the government. There are no exceptions. You cannot do the work you used to do. You cannot do some other type of work. Your disability will last at least one year or result in your death.
So if you worked in the circus and walked a high wire and you cannot maintain your balance, then you cannot continue doing the work you used to do. However, if you can sell tickets for entry to the big tent, you can do some other type of work. However, if your physical therapist says you are doing so well, you should be back on the high wire in 6 months, then you will not get disability. If you are dying, it takes about 6 months to get approved, and you will get about 6 months of payments and then die. Generally the deck is stacked against you. Before you fill out the multi-page application form, ask yourself if you are disabled according to the government rules.
If you really believe you are disabled, then apply. Do not write on the forms at first. Write your answers on plain paper and read it two days later...does it still make sense to you? Rewrite it, reread it, rewrite it, reread it...does it make sense? Can you demonstrate that you cannot do your old job, or even do a new job, or are you dying. These are the questions YOU have to answer.
SS will get your doctors information, physical therapy, etc. You will be sent to a government contract doctor to test you, maybe more than one doctor. I went to two contract doctors.
They will contrast your report vs your doctors statements vs the contract doctors statements and make a decision.
THE MOST IMPORTANT PART IS, DO MATCH SSDI DEFINITION OF DISABLED?
There is no retro active pay. You will be declared disabled when you are approved by SSDI. It has nothing to do about when you quit working. If you have an attorney, generally they will paid by the SS. I was on SSDI for two years, and then started on medicare on my second anniversary.
You are filling out a legal document. It is a felony to lie. Do not make any false claims. Do not expect your congressman to help..it is out of his/her hands...there are rules. If you have to reapply, they will contrast your first application vs your second one. That is why it is important to write and reread your application several times over.
I hope this helps someone.
James