My boyfriend and I took a vacation from July 22nd to the 27th. At the end of June, I had started taking bc pills and, just my luck, my period was supposed to start the same day as our vacation so I didn't take my sugar pills and just kept taking the hormone ones and delayed my period. I want to say it was the 23rd or 24th we had unprotected sex, but I was on the pill so we didn't worry, however a liberal amount of drinking was done on this trip and I realize that can sometimes effect the effectiveness. 

The 27th, I started my period however it was lighter than usual. 

Now, it's been about 3 weeks and my breasts are very tender. My cervix is high and closed. I also have had a decrease in cervical mucus and have been struggling to get wet even when aroused, which is never an issue. I am not do for my period for 15 more days.

I have read that it is rare, but some women will still have their first period if they conceived extremely close to the start of their period which is the only reason I am even slightly concerned. I don't want to waste a test (as I have several times in the past) if it is completely impossible. But if it isn't impossible, I don't want to ignore the signs and continue to take my bc and cause a miscarriage. 

Thank you for your time and answers ahead of time, I very much appreciate it.