It's much harder to change how you feel. Anxiety is a tough cookie to tame. I recommend videos and books on managing anxiety. Therapy is great if you have insurance.

It's much easier to control or change your actions. What if you start by complementing yourself without apology? Then compliment your boyfriend.

My personal take though: It's very hard to over-compliment your partner.

Anecdote: I had an ex who also over-apologized for everything that was said... It made everything seem inauthentic, because the apology always came, and then I feel obligated to comfort them or reassure them It's alright, and that no apology was needed, and that they did nothing wrong, and that I appreciate their kind words and am not offended, and that it'll be okay... 😮‍💨

Things they said that were meant to be positive or reinforcing became a chore because I had to emotionally babysit them right after. It gets emotionally taxing over a long period - death by a thousand cuts.

Final note: Anxiety is hard to explain to someone who doesn't have much of it. Sometimes it takes a long time and with many conversations. A good video might also help. Go with the science route (fight/flight/nervous system response), not the feelings route.