I'm On Birth Control And I'm Supposed To Be Getting

I'm on birth control and I'm supposed to be getting my period right now, but it's only been a little bit of brown spotting for the last two days.

I have missed a dose one time, but I took it about 15 hours later, and I have used a condom every time I have had sex with my partner except for one time, but that was about a week or more apart from when I missed my pill. And he had also already came before we had sex without a condom, and he had cleaned himself up before we had sex a second time without a condom.

Is there any possibility that I am pregnant? I have been on birth control for four months now, so it should be regulated. But I want to be sure before I begin to worry.