Past-relationship OCD

I've been broken up with my ex-fiancé for over a year and a half. We were together for almost five years. We decided to end it because we both weren't happy. As much as we would try, we both couldn't come to some consensus on how we wanted to do things. It was an amicable breakup, and there were no hard feelings during it. Now that time has passed, lately I have been thinking about her. I go through the usuals of what went wrong during the relationship and the many what-ifs that either I or she could've done differently. But there has been one particular aspect that has been bothering me lately, and it has wormed its way into my usual OCD frenzy. When we did break up, we did spend a couple of nights together. After that, we would go our separate ways. For some reason, though, a fear would pop up. A fear that I got her pregnant, and that after all of this time now, she is with my child, and I have no idea about it, and it's been wracking my brain ever since. Here is the kicker, though, looking through her social media, everything that she posts and has done since indicates nothing - ABSOLUTELY NOTHING - that she ever got pregnant or has had a child. Even a friend of mine has looked through her social media and has seen nothing about a kid or anything like that. But, yet, for some reason, in my head, I have convinced myself that she was so diabolical enough that if she did get pregnant, she would make sure that she doesn't put any trace of that child on the internet so that I might find out. And, the real obsession here is the fact that I feel like I need to communicate with her and ask if I ever did get her pregnant. It's absolutely insane, and it has been wracking my brain for the past month. And while some days are stronger than others, I try to tell myself that even if she was pregnant, she would let me know about it, there would probably be some legal implications, and I would assume that her family and my family would be on me knowing that I have a child. But, yet, nothing indicates that she had a child. I should also add that she has PCOS (Polycystic Ovary Syndrome), and we were even using birth control during sex. I also didn't want children when we were together anyways. And, yet, despite the evidence, despite everything that proves that she doesn't have a kid, my mind says otherwise. And, I know it's an OCD thing for how I keep ruminating, and, unfortunately, fallen into the compulsions of having to look up her on her social media and get that answer that she didn't have one. What are some better tips that I can try to deal with this? I am tired of thinking this way, and it has hindered how I have been doing things lately. Sorry for the lengthy post, I am trying to get some better insight.