Missed period but I haven't had sex since beginning of September?

Hi!

So last week I was supposed to start my period, but I had nothing. I haven't had sex since September 10th so I am a little puzzled.When we had sex, I am on birth control and we did use a condom. My period came in September and on Halloween. When I was taking my sugar pills I did take them every other day because I forgot to take them, so I was thinking that maybe since I took them infrequently, maybe it caused my period not show up.

I have been to planned parenthood since then for a check up and for a birth control refill and when they did the urine test test for stds, I never got a call back from them but I do not know if they would call if you're pregnant.

Now this week, my boobs hurt and it could be because of weather change because I guess temperature change can do that.

I am just really confused as to what is going on and I am hoping that I am not pregnant. I know stress can be a factor and I am pretty stressed because of finals and worrying about my period and depressed lately.

help me!