First time unprotected.

I have been seeing this guy for 9 months (our relationship is complicated), we have sex a couple of times but it was protected. So two weeks ago was our first time without protection (I was stupid because I couldn’t wait for him, o know stupid) he did it for a wee while but then placed the condom on. He knows I’m not harbouring anything like STDs and he told me that he doesn’t have any because he uses condoms when he’s having sex. I don’t know whether to believe that. He’s my first time and I was wondering would I be more prone to catching an std? I would say I am ( I need to get tested but I’m scared incase it is positive) but I just wanted to know what others thoughts on it. I’m just wanting to know because I’m just starting to become sexually active........