2nd month on Yasminelle and no period

Ok I'm 17 and I just started taking Yasminelle birth control on 17th Feb 2007 at 6.30pm every day. I bled constantly for my 1st month, light enough bleed and for 3 or 4 days during my break week (10th-16th March) I bled very heavily. I started taking my next pack on 17th March 2007 but did not take 1st pill untill 3am on the morning of the 18th. That night I took my 2nd pill at 6.30pm. That night I had sex. We tried unpotected but neither of us were comfortable so my boyfriend withdrew and put on a condom. He was only in me for at the most 20 seconds and did not come in me. We had protected sex the following weekend. Now I have finished my 2nd pack and am 4 days into my break week with no period. My discharge has change texture in the last day, I was very gassy last week (a typical period symptom for me)and my breasts have been sore all month. Last week I was under a good bit of stress (I know how can a 17 year old be stressed). Just slightly worried that could be pregnant. Had big scare last Jan when I was 2 weeks late so went on pill. Please help me put my mind 2 rest.