Sex delay Period for a month?

So I'm 21 and I missed my period this month. I usually have irregular periods but my last one started on the 28th of March and lasted to the 2nd of April. My boyfriend and I always use a condom and it has yet to break. I just started taking some medication and I'm wondering if that could also affect my period. I haven't taken a pregnancy test but I'm terrified to do so. I've heard that sex could possibly delay periods and was wondering if that was true? I'm also stressed from finals and this missing Aunt Flow. Please help!