Hello, I am 18 years old and I was prescribed doxycycline for my acne and have been using it daily since April 18th. My boyfriend and I have been sexually active, but we use a condom every time (that is our only form of contraception). After each time, he checks to make sure there's no leak and there hasn't been. Our first time was May 3rd, I got my period May 5th and it ended on May 8th, which is one to two days before it usually ends. We had sex 4 times while on my period. My cycles range from 25-27 days, averaging at 26. I was supposed to get my period 3 days ago but I never did. I noticed that my boobs are tender, especially my nipples, and they are swollen. I heard this is a common symptom of PMS as well as pregnancy, but I have never experienced this symptom before any of my periods. I also have been peeing a little more often than usually but it may be me being paranoid. I have had a few small cramps which I usually get before and the day of my period but it hasn't come. I heard that doxycycline can potentially delay your period, but I am worried I am pregnant. I haven't taken a pregnancy test yet because I heard you should wait a week after your period was projected to start for more accurate reaults. Should I be worried? Am I pregnant or is it the medication?