Chance of pregnancy on the pill and still have my period.

I am on the birth control pill, although I will admit every once in awhile I accidentally take it a little after the normal time. I haven't pissed a period, but the last two months have been slightly lighter than usual. Although it still has been normal colored.

The last time I had sex was early October 30. He used a condom Saturday night, but in the morning he didn't. But he didn't finish inside me either. I got my period as usual on November 9th. I actually took a pregnancy test November 14th out of complete nowhere, other than the fact my best friend told me about the show "I didn't know I was Pregnant." It was negative. And I thought everything was good! The last week of November I had some cramping, but I was also very stressed with school. For about a week, I really wasn't feeling well and sick to my stomach, but it went away after a week. I actually took two more pregnancy tests that week on different days, and they were both negative. I got my period on time December 7, but it was a little lighter again. I've taken three pregnancy tests and they've all been negative. I don't have any symptoms anymore other than my right boob feels funny, but I don't think tender or sore is the right word.

I'm under a ton of stress with school, so I'm hoping this is the reason why I am so concerned.

I literally can't sleep or anything I'm so worried! The last time before the end of October I had sex was in the beginning of September for about a week and then a few times in July. My period has been normal this whole time up until the last two times, and I am concerned. I honestly think I'm most likely psyching myself out, but I want to make sure.