Does my fiance have "houdini sperm"?

Okay heres what happened: I'm set to have gastric byp surgery in a week (everyone knows you can't be pregnant for surgery) well because of the risk for blood clots I had to stop using my birth control for a month. So when me and my fiance were intimate we used a condom. When we were finished I went to take the condom off him and noticed very little semen in it. I was scared thinking that the condom broke. Well I went into the bathroom and ran water in the condom...no leaks...I was puzzled. Where did his sperm go? The only thing we can think of was the fact that he is uncirsized and he says when he went to the bathroom afterwards a glob of semen came out when we pulled his forskin back? I have anxiety disorder and I spaz about getting pregnant all the time. I would just go by a test but they're going to do one at the doctor tomarrow when I got for my pre op testing. I'm just so terrified of hearing her say that I'm pregnant. Now I know you can't tell me if I'm pregnant or not but you can tell me what to think. Should I be worried...would you be?