My boyfriend has a high body count

My bf is 20 and I'm 18 this is my second serious relationship... my first one ended very badly as a result of him cheating... a year later I am now with my new boyfriend and we've been together 4 months, we click very very well and I really like him ... I have only slept with 3 other guys than my bf but he has slept with 30+ (he's not sure :/ ) and that kinda bothers me... it makes me insecure because I'm 1. Younger 2. Less experienced and 3. I don't know any of the girls (he won't tell me) .... he doesn't seem to get this though.... I know many girls have slept in his bed and I get sorta uncomfortable sleeping there and I've told this to him... I also requested that he gets tested and I even told him I'd go with him (even though I've been tested before) , we always use condoms but now that we're getting more serious I'm on the pill so I don't care if he doesn't wear one.... when I asked him to go he got very defensive and told me he doesn't have anything and would know if he did , i asked for him to go just to be safe and he's still fighting me on it and turns the fight on me to say that I'm making him feel like shit... I don't want his past to effect us but I don't wanna be in a relationship with someone like this... any advice on how to handle this and how to stop being so insecure about his past ??! :)