Numbers??

I'm with a guy a couple of years older than me, he's in his last year of uni and I'm going in September. I know he's slept with at least 8 girls (not much for a guy of 21 at uni) but I know there's more. I've slept with 3 and he knows this. Sex is very important to me and I've only ever done it with guys I've been serious with. But not knowing how many he's slept with is starting to pull at my curiosity and I think I think it's worse than it is. But I'm worried that isn't not, I don't feel special which is ridiculous because he's lovely. But with sex meaning so much to me it hurts knowing it doesn't with him. Any advice on how to stop these silly thoughts?