I Have Been On Birth Control For About 6 Months.

I have been on birth control for about 6 months. Recently, my cycles have become very irregular. I have bled three times in December, but my most recent bleeding was heavy and lasted three days. This took place during the inactive pills in my pack. If the last time I had sex was Dec. 17 and I have bled two times since then, could I be pregnant? My partner and I use condoms and the pill to be protected.