Intrusive thoughts

I’m with my bf rn and I’m having intrusive thoughts. I’m also questioning how I became this way and developed relationship OCD. I’m having some sort of identity crisis. I’m so fuckin insecure. I’m worried he likes someone else. I’m thinking about how this all started. I assumed I was triggered by my past relationship (back in high school). But, what if it was triggered by something else from my past that I don’t know about clearly? I’m trying to remember why it hurt me so bad that I became this fucked up

Any advice? Please and thank you!