A little worse on important days

I've been going through hell for months and months. Recently diagnosed with BPD, suspected OCD that kind of switches between Real Event and Relationship focused, but of course also I doubt whether I have OCD at all and the relationship focused stuff is actually "my gut" or "my subconscious" or whatever. Started Prozac a few months ago. For the past few days, I've actually been feeling really good. Less rumination, less drive to "figure out" the questions and doubts that pop into my head. Less desire to "investigate" my thoughts and waht they mean. A bit less "testing" of my feelings as well. So I was so happy, because I felt better just in time for my birthday! Like yesterday, I felt pretty consistently ok and almost had the feeling that maybe I do know myself, maybe I can trust myself to know what I want. But today is my birthday, and I feel a bit worse than yesterday :( My gf took me on a surprise little sailboat tour, and it was so fun and I had a good time and I am so grateful, but I could feel that sense of uneasiness taking me out of the moment a bit. The worries about all of the things I have thought and doubted in the last few months, and even if everything gets better, I don't know how to deal with the fact that I got to the place where I was questioning the things I was questioning and doubting my relationship so much. Do I feel a bit worse because it's my birthday and there is some "pressure" to be present and have a good day? Just wanted to know if anyone else could relate. I really want to be able to just let go and enjoy the rest of my bday with my gf. She is so amazing, and she's taking me to a surprise dinner and I really just want to fully be in the moment, no matter what! Once again, I doubt my OCD diagnosis especially since my decade relationship has been through so much shit due to me being a bad person and very dependent. I am trying to learn how to love my girlfriend more healthily and selflessly, and the change/growth can be a bit destabalizing. So I'm sorry if I shouldn't post about ROCD stuff if I'm not 100% on a diagnosis, I just relate a lot to the community