AMEN! Sounds like me! I've done classes and actually done some FMQ that worked, but right now I'm in the SAME spot you are in. Went to the county fair helping our guild demonstrate quilting, folks watched me rip apart my most recent FMQ failure and someone suggested it was time to change to a new needle. Trying that next to see if I can get out of this FMQ problem rut.
Sometimes you just have to stop, step back, and let the project get cold before you try again. I would suggest classes, or do like I'm doing - work on piecing for awhile to get some successes back in your life... until you feel better/ calmer/ happier and can get back to it.