Though I'm not a doctor, the one thing I know about psychiatric drugs is that it is hit and miss. I saw a documentary where a psychiatrist said that unless you have an immediate family member with the same disorder who has success with a particular drug, they basically just guess - hit and miss until they find something that works.
And since so many of these drugs take several weeks before you see results, it can take a long time to find the right medicine and the right dosage.
One thing you can do is keep a drug journal - what you took on that day - what worked - what did not work. That should help your MD nail things down.
And just be patient and communicate with your MD. There's lots of drugs out there and you and your doctor should be able to find the right mix, it just might take some time.