Sex Shrink

I've never been able to finish while wearing a condom. I have tried multiple kinds of condoms, different positions, etc. etc. Girls (and me) are often frustrated and at some point we either give up after 45+ minutes of "are you done yet?" or her being ok with finishing me somehow. I don't want to stop using condoms but I can't find anyone else that's had this problem. What could be causing this?