Yes there is a chance you could be pregnant. Anytime you have sex or exchange bodily fluids with the presence of sperm you can become pregnant. The best thing to do is to at least not have sex until you start your period or are late. If you start your period and it is normal then chances are you are not pregnant. If you are late then take a test first thing in the am, if it is negative and you still don't start then wait a week and retest. If all else fails go to your doctor and get a blood test. I am not going to tell you to use protection mainly because it is a false sense of protection anyways and also because you are not married. I am however going to tell you that if you do not want to be told to not have sex then you should get married. In all honesty what answer would best fit you? I mean if you do not want to get pregnant and you don't want to be told to use protection or to not have sex then what do you want people to tell you...jump 3 times spin around and snap your fingers then tell your fairy god mother that you don't want to be pregnant? Sorry to be so sarcastic but if you do not want to get pregnant, and if you are not married then you really shouldn't want to, then you need to be willing to hear the real way to not get pregnant, not having sex. Now to the what can cause an irregular period...have your periods ever been regular and if so how long have they been regular? Is the irregularity recent? It can be caused by change in diet or exercise, stress, and depending on how old you are it can be regular hormone changes or fluctuations. Here is the number to a place that can help you with a FREE and CONFIDENTIAL test. 1-800-395-HELP, Optionline will give you the number and location to the closest pregnancy resource center to you where they will give you advice appropriate to the answer of your test...like I said sorry to be sarcastic, that is kind of my personality, I hope this helped at least a little bit...Love Meg