I don't think urinating matters here. What matters is that there is a possibility (remote but not zero) that pre-ejaculate (which can contain sperm) was on the outside of the condom when you turned it correct side out. And then you had intercourse.
So, yeah, get Plan B just to be on the safe side (it's cheaper than pregnancy or abortion, yes?) and, next time, insist on there being more than one form of birth control when you do it. Condoms are not a great single means for preventing conception, although they are a lot better than nothing.