I have missed my period 2 months in a row, and now am supposed to have my month 3 period, yet 4 days in and it's still not arrived. The 2nd month I spotted a little for 3 days, but not during the time I was supposed to have my period. I am on the pill. I have tried 3 pregnancy tests at 3 different times and they all say I am NOT pregnant. Could there be another cause for my irregularity? I am not feeling like I am under an unusual amount of stress, and I also have had no changes to my body or emotional health.