I am in a very similar situation as you. If you have ADD, my initial advice is "good luck!" My process went as follows:
First, I had to go to my doctor and asked to be officially taken off of the medication. Next, I went through a 90 day waiting period. During that 90 day waiting period, I met with my AME. Your AME must be HIMS certified. He gave me my physical and all other aspects of my health checked out. Out of pocket cost for physical and using him as my case manager was \$600.
After the 90 days, I took my aviation neuro-psychological exam. This exam usually lasts 7-9 hours and insurance does not cover it. My out of pocket cost was \$2500. Within 24 hours of my neuro-psychological exam, I had to have a urine drug test done. This test must be done under direct observation; otherwise it is not valid. This only cost \$100.
About a week and a half later, I met with a psychiatrist. This was about a three hour meeting that cost me \$550 out of pocket. This test was to determine my personality, check for alcoholism, depression, etc.
Unfortunately, I was still not done after that. The way the neuro-psychological exam is set up is that if you don't do at least average on one section, then you need cognitive therapy. My scores were superior and high average on all but one section and I got the therapy recommendation. They gave me an IQ test in which I scored a 138. That's an exceptional IQ, but somehow I cannot pass this test.
Right now I'm waiting for my AME's recommendation and my the psychiatrist results. Pretty sure I'll need therapy. I've been in flight school since July and my CFI has been ready to let me solo for months now. The whole process is pretty screwed up. Looking back, I should have kept my mouth shut.