What Causes Spotting Followed By Heavy Bleeding After Taking Plan B?

I had sexual intercourse on the 10th (around the time I should have been ovulating). Then again on the 14th. There was a hole in the condom on the 14th so I took the Plan B pill. I bled lightly on the 22nd and a bit heavier on the 23rd, then the bleeding stopped. Could I be pregnant? If there possibly a hole in the condom we used the first time?