is this OCD, or am I just making up for past mistakes?

Hi! I was diagnosed very recently with OCD, and I'm very confused. All the symptoms I was showing were described to me as being irrational thought patterns, but I don't feel like I exhibit any "irrational" thinking. I explained to my therapist that I frequently apologize, deal with intrusive thoughts & that I started questioning my morals at a young age, and it was starting to get in the way of more important things in my life again. This prompted her to contact my psychiatrist after the session, and I had an evaluation the following week. The questions on the evaluation, though there weren't that many, resonated with me in a way that felt almost uncomfortable. I ended up receiving a diagnosis of OCD, and I really don't know what to do. I feel like I can tie most of my obsessive thoughts & subsequent behaviors to a few specific things I've done wrong in my past, and I really have never heard of an OCD case manifesting itself that way. I just know that I need to hold myself accountable, and I'm very confused as to how that relates to OCD. Is it possible I was misdiagnosed? Is this just something I'm unfamiliar with? Any advice is greatly appreciated.