Missed period but breakthrough bleeding. Could i be pregnant?

I've been on birth control for awhile but i missed a lot of pills last month and so i just stopped half way through to wait to start a new pack. Me and my boyfriend used another form of protection in the mean time. When i started my new pack i made sure i took it EVERYDAY! I had breakthrough bleeding a couple times but only for a few days each. Then when i started taking the brown pills my period never came. Is it possible i could be pregnant or is it just because of the breakthrough bleeding? Any advice you can give me would help A LOT! Thanks