This a good place to hang out When you say GP, you mean general practitioner?

This is my experience as I have BPD. It and Bipolar can be hard to diagnose and missed. ADHD at an early age is heavily mis diagnosed, as I was.

I never was accurately accessed and found out until i was 36, 20 years later. GP's have NO BUSINESS diagnosing disorders. I found a amazing DR and Psychiatrist that specialized in Bipolar and BPD. I did a full eval with him for 2 hours.

I would possible find a therapist that specializes in BPD and DBT. There you may find a referral to a good DR that may have clear answers and a path to make it better.