Missed period

So I am irregular with my periods and just started birth control (the pill Apri) about 4/5 months ago. Well I am two weeks late on my period. I have taken 5 test since the day after my period all the way up to today and they are all negative. Am I just over reacting or should I truly be worried? Every time I have sex there is a condom and I check it for holes before and after.