Piggybacking on what Bipolar Wolf said, I've researched this topic a good bit. Researchers aren't sure if it causes psychosis or if it triggers an underlying issue. Many studies have shown the more you ingest, the more susceptible you are to it so that falls in line with your heavy usage during the period you first experienced psychosis.

The THC works with your seratonin and dopamine systems. Antipsychotic drugs do as well. MJ essentially slows everything down, but your brain eventually compensates. You then become hypersensitive and mania begins. That's the working theory anyway.

My therapist told me almost all of her bipolar patients use MJ. She said she suspects several of them would be fine if they would quit, but that they keep triggering episodes with continued usage. They have no history of mood disorders otherwise and mania set in late in life compared to typical bipolar patients. Your onset at 44 isn't unheard of, but it is later than most.

My advice would be to keep doing what you're doing and leave it alone. It is clear your mind is sensitive to it and it isn't worth risking another episode. My hope for you is that you can stay in remission if you stay clean.

Here's a psychiatrist's take on it.