Not diagnosed but showing a lot of signs of BPD. How can heal on my own whilst waiting for a referral?

The referrals in the UK stake a while, in the mean time I want to save my relationship. The worst part about suspecting I have BPD is having severe anxiety about my boyfriend leaving me, taking every piece of Cristism as a personal attack, the black and white thinking. Overthinking everything and then feeling incredibly low. i just want to feel healthy in my relationship, it feels worse since being in a relationship because I was never hardly triggered single and and If I was having an bad time or spiral I would lock myself away untill it was over and no one even know. I get told I’m overally emotional and sensitive too. Any self help books YouTube channels suggestions would help