You do have a physical problem. You have a brain problem. The problem isn't about your mental ability to think, if that were the case, you could think loving and peaceful thoughts, and then life would be fun and normal again. Although it is important to manage how you think, since negative thinking tends
to draw negative experiences, your brain will not repair itself due to a new set of positive thoughts. People who are chronically depressed or anxious have distorted brain sizes around the hippocampus. For you, when you were younger, you proabably experienced what you thought was a traumatic experience at the time as a child, and that experience stressed you out. Although you eventually grew out of that fearful experience, your brain didn't. Meaning the emotional stress from your childhood more than likely affected how your brain formed by the time you became an adult.
When you started Effexor, which I guess was after high school, you were assisted by the medication to manage the distorted brain sizes. Once you got off, the Effexor, after five years, your brain returned to its dysfunctional state prior to the medication. It was distorted from the earlier emotional trauma that occurred, during your growing up years.
If you really need to convince yoursef your brain is the culprit, and that your brain hasn't been responding like a normal brain should, I suggest you get a brain scan or a brain MRI. If done by the right doctor, the scan will show you where your brain is weak in size, and how distorted sections of the brain affect the brain's response rate.
Your bio states you live in New York. You may want to goggle Amen clinic, since there is a center in that jurisdiction. A competent brain doctor can do a MRI on your brain, and provide important information on the status of your brain, and the needed recommendatons to manage its distorted state.