You might think about posting on the anxiety forum, as you say you're an anxiety sufferer. This isn't OCD. Obsessive thinking is found in all cases of anxiety and depression or they wouldn't exist. While nobody here was there so we don't know what happened, it doesn't sound like you had sex with anyone. You would have known. It was a public place. You'd know. If you found yourself on a bed in someone's bedroom, well, you might have some reason, but not in a bathroom in what sounds like a crowded bar. Again, not only you but everyone there would know. But that doesn't deal with your anxiety problem. Is it like this often? Because if it is, are you in treatment for it, in therapy? Also, not to scold, but you're pregnant now, you can't escape by drinking yourself to a stupor anymore. If that's one of your coping mechanisms, you have to find an alternative. Let us know what you're doing to stop thinking like this, and again, there is an anxiety forum that has more traffic than the OCD forum usually and you aren't describing OCD. All the best.
Intrusive thoughts can be ocd and do not 'always' have rituals so we don't know if you do or don't have ocd and can't say one way or another. That's between you and a doctor. My 2 to 25 cents on that matter. However, I agree that this sounds like an anxiety issue. You perhaps have an obsessive thought process? Is that what you are referring to?
First, honey. You need to address your life style. I know I'm not saying anything you probably don't know but getting so drunk and high? Just not safe or healthy. If you are not in control of yourself, you shouldn't be out in public. Period. We don't live in a super safe world where being at a bar out of your mind drunk is Coolio. So, really, no more of that. And are you trying to get pregnant? Maybe that is no big deal to you? But in general, a thoughtful approach to starting a family and using birth control until you think it is a good time often works out best for everyone. This is NOT a lecture but girl to girl advice. Nothing has changed the trajectory of my life more than having kids. It's HUGE.
Now, to your concerns. I just doubt it. Of course, I don't know. But I sincerely doubt it. Unless you have some reason to suspect after the baby is born, I would not bring this up to your boyfriend. And I would work hard to address your anxiety. since you are pregnant, I'd avoid medication now (but you may need to circle back to that after you give birth as that actually for a lot of women is a very anxious time and post partum is a real situation (and can be dangerous)-- keep in good communication with your ob/gyn about that but you may consider counseling. They even do online counseling now which can be more economical (done via skype or platforms like that). But I'd go ahead and talk it out. Your fears sound slightly irrational to be honest which is often the hallmark of anxiety. hugs