Hi: I am on Social Security Disability for major depression. You generally get more money on SSD than SSI. However, since you probably have not worked much, I don't know how much money you can get from SSD. At least, it is a question to look into.
What you need for SSI is usually three things. One, medical records to show that you have been sick. The records should be as complete as possible. Two, it helps to have a doctor support you for SSI. Generally, the doctor will have to fill out a fairly form about your illnesses and the severity of these health problems.
Third, in many cases, it helps a lot to have a lawyer. I suppose it also depends on what state you live in. I live in NYS and having a lawyer was very helpful for me to get SSD. Also, I got it much faster than if I did not have a lawyer. Without a lawyer, I am sure my case would have dragged on for 2 to 3 years. In NYS, a lawyer cannot charge you a penny unlessyou win the case. The money they might win in your case is modest. Try to find a lawyer who specializes in SSI or SSD.
Unfortunately, in some cases, it is more difficult to prove you have a psychiatric illness, rather than a physical disability. How exactly do you prove you are depressed to someone who might think you want SSI so you don't have to work? So the fact that you have IC and diabetes and take 12 meds a day is something that will strengthen your case.
I am so sorry you are facing so many health issues. You are definitely a strong candidate for SSI or SSD. If you need further help, I guess you can email me. However, my time to spend on emails is fairly limited.
All my best.