Am I pregnant or just irregular?

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 (like bleeding through my clothes!!!) and lasted three days. This took place during the inactive pills in my pack. I'm feeling bloated, but no other symptoms. 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. Am I just being too paranoid?!