Hello, I Have Recently Just Started Doing Things With My

Hello, I have recently just started doing things with my boyfriend and just a week ago we first had sex. He wore a condom and it lasted only about 5 seconds at the most, and the condom had no holes in it, and was empty and had nothing on it (apart from the lube on the outside). He has never finished around me as I have never made him finish and so although I dont think I could be pregnant, I have missed my period by two weeks (bare in mind I missed my period before we even had sex) but I want to put my mind at rest. Could you help me please? Thanks.