Right. I would suggest doing a pregnancy test. If he came and then put a condom on, he could have pushed the sperm into your vagina. It's not always as easy to get pregnant as you would think (i am now find this) but you never know.
However, if you have been worrying about this, it's possible that your body is playing tricks on you. I haven't had a period for two months now, but am still not pregnant.
I hope that you get the answer you want. I would suggest taking control of the contraception side of things yourself. Get on the contraceptive pill, and always make sure that the man has a condom on....And that you put it on him to make sure that it's done right. I have always done this, and have never had a problem.
Good luck and I hope you get the answer you want.
Xx