Sexual partners

My husband has had several (25ish range) sexual partners (mostly casually) whereas he's the 6th person I've ever been with. We're in our late 20s. Lately I've been struggling with how high his number is (in comparison to mine.) It's likely connected to me being 2/3 of the way through our 3rd pregnancy and just being in my head and extra emotional. Anyways, I've always viewed sex as an intimate, personal thing whereas he viewed it more for just fun. I know it's just a difference in opinion and neither of us is in the wrong. I'm not a prude and he's not a manwhore. I logically know there's no reason for me to feel upset about it and there's nothing I can do about it anyways. I did know before we started dating so it's not like it was a secret. It's not going to end the relationship or anything, but it does take up space in the back of my head. Idk why it bothers me so much. He treats me well, but I can't help but feel like I could just be another notch in his bedpost, esp when we do get on the topic of previous sexual encounters. Any suggestions on moving past it for my own mental health?