Loestrin 24 fe and planb...now period is late

I have been on loestrin 24 for 7 months, but i have been on birth control
for 3 years. recently i became sexually active. My last period started on October 28, 2009. Since my period ended my boyfriend and i have been sexual active. On November 12,2009 i started to have some bleeding. It was brown and then turned red.The doctor told me it was breakthrough bleeding due to my birth control. I had unprotected sex on the 21st of November. My boyfriend pulled out but we did not use a condom. I was beyond scared so I took planb. I was told, I most likely did not need planb because i take my birth control regularly. I still took it to help me settle my mind. The day after i took it, i noticed clear discharge. I am now on period break and nothing is happening.I have had lower back pain for the last 3 days but no period. Tomorrow I start a new back of birth control. What is going on? Where is my period? Did the birth control and planb fail? I thought the birth control stopped me from ovulating?? anyways, i am beyond scared. Please let me know of any information you have. Thank you so much!