What Causes Irregularity In Periods After Taking Contraceptive Pills?

Hi, i just making an inquiry online regarding pregnancy. i took the contraception pill back in December 2010. since then i have done 2 pregnancy test that have been negative. Last month in February i had a period and now i am currently going through a period, however my period is very light at the moment and its the second day into it, im not experiencing no periods cramps what so ever. Am i just freaking myself out and stressing or is it normal for my period to be like this?

hope u can help me

kind regards