What Causes Delayed Periods After Having Protected Sex?

Why is my period taking so long? The first day of my period was March 10th, It is now April 12th (I'm on day 33) & still nothing. I had protected sex 3 times around ovulation week. Once before I saw white discharge (so that I knew I was ovulating) & twice a few days after that. Im 17 & irregular, but I know that I ovulated because I felt ovulation pain in my lower sides. I am getting pms symptoms (pooping alot more..now turning into diarreha, tender breasts, moody, tired, headaches) I was expecting my period last week because I know that people should get their periods 14-16 days after ovulating. This week just started, so I should wait it out.. Im just wondering if Im preg or not.