I am sorry you and your gf both suffer from mental illness. She is getting help for her bipolar condition. If you suspect you have borderline personality disorder, get yourself to a therapist and a psychiatrist stat!
My daughter has BPD and it's a horrible disease. Borderlines usually have several diseases going at once: severe anxiety issues, low self-esteem, self harming, substance abuse, OCD, bipolar, ADHD, etc. It's a really tough mental state.
Perhaps some anti-anxiety meds/mood stabilizers and weekly therapy would help you learn to be a calmer person and a better partner.
My heart goes out to both of you.
Love withers under constraint; its very essence is liberty. It is compatible neither with envy, jealousy or fear. It is there most pure, perfect and unlimited when its votaries live in confidence, equality and unreserve. -- Shelley
Mags (poly, F, 61) loving miss pixi (poly, F, 39) since January 2009, living together since 2013
In a newish relationship with Steve, (34, poly)
"Master," (mono, 34), miss pixi's Dom for 3 years