SSDI benefits are not awarded based on when you apply. They are based on the date when SSA decides you became disabled, usually based on information provided by your doctor(s) or when you prove you became unable to work.
There are 3 phases. Initial filing and review of your case, a second review if you are turned down, and a hearing if you have been turned down a second time. Age is a factor. If you are older, you are more likely to be approved in one of the initial stages, and are less likely to have to go through a hearing. The experience your doctor(s) have with the process, and their good documentation, are factors as well. Since the process can be very long, you can be eligible for back payments based on the date SSA decided you became disabled, and when you you have been approved for benefits. A lawyer will take a percentage of that sum if you hire one, which I suggest you do if you decide to file and are denied in the initial stage. There's a cap on the percentage they can take, but I forget what it is. You aren't eligible for Medicare immediately. There's a 2 year waiting period from when you have been declared disabled.
The amount of money you receive is based on how much money you have made recently, paid into social security, and some other voo-doo they do. It will not be a lot. Everyone
should get a social security statement every year that tells them the amount that they would receive, but it usually goes in the trash.
There is a "ticket to work" program that allows SSDI recipients to make up to either $900 or $1000 a month without losing benefits. I don't know the ins and outs of it though. I don't know if you can qualify for the program immediately.
I think it's a very wise idea that you are having your husband accompany you to the appointment so that he can hear from your pdoc the extent to which everything is effecting you, whether or not you want to go on disability. He needs to hear it laid out clearly from someone else... to hear that your situation rises to that level, and things are that difficult for you


I hope the appointment goes well


And I hope you have managed to continue to get some good sleep