December 4, 2016 cycle day 1 for me, that period lasted for six days. December 15, 2016 I had PROTECTED sex and he pulled out before ejaculation (even with the condom on). The whole time we were having sex we were protected. I am not on any hormonal birth control pill so my period varies. Ever since I became sexually active, the latest I have went waiting for my period was 5 days (what i mean here is, I was 5 days late). On December 15, before having sex I already felt sick due to the flu that was going around everyone at home. December 16, the flu hit me, I didn't feel good, cold, headache, feverish. I was supposed to ovulate sometime that week but I did not. I noticed that I ovulated December 29, 2016 (cycle day 25). January 1, 2017 I was supposed to get my period. 5 days later I didnt get it so I bought pregnancy tests. I tested at 7 days late and got a negative. I waited even more, at 10 days late I tested again and was negative. 11 days of being late I already felt like dying, wanting to give up on life because I dont want to be pregnant at this age. I got my period lunch time and was the happiest. It was a real period, bright red blood, filled pads and normal flow. After that I promised myself to not have sex as I realized I was not ready. I put myself in so much stress and depression. After my period ended, the paranoia never ended, I had to wait for my second period to confirm it to myself that I was not pregnant. Even after that period, negative pregnancy tests, I was still scared. All in all lesson learned, don't have sex when you are as paranoid as I am. Periods can be late due to several factors, dont research everything online as it will only make you more parnaoid.