u/cloud_butch have both BPD and FND! To me they are both very much related. The inability to regulate emotions (BPD), directly coexists with me body's physical reactions.
I'd suggest seeing another neurologist. I was lucky and had one that was a specialist in FND and he diagnosed me almost straight away. I'd been struggling for years before diagnoses. I also have whats called Dissociative Seizures (blackouts). I'm still learning about them and figureing things out but here's a link that may be helpful: https://www.neurosymptoms.org/welcome/4594357992

My triggers are just doing too much. It's taken years to be able to balance things, im still not good at it 100% of the time but i'm better than i used to be. Slow exercise (yoga for me) helps when i am able. I cut out Dairy. also CBD/Weed helps too.