Hello there The most important pills not to miss are those just before and after the 7 day break. So if you have missed any of that dose then pregnancy could be a possibility more because you even had unprotected intercourse. Also your symptoms of breast engorgement and discharge support the chance of pregnancy. Still if your urine test for negative, I suggest you to repeat the test after you are a week overdue. The other possibility can be a side effect of long term use of pills. The heaviness of a menstrual flow depends on the thickness of the lining of the uterus just before the onset of menses. The thicker the lining, the heavier the flow. If you are using low-dose pills(for example Ortho Novum, LoOvral, Ovcon, Loette containing 20ug estrogen), there is a tendency for the uterine lining to become very thin, over the course of many months. Clinically, this is reflected as lighter and lighter periods which may even stop completely. This is not a dangerous condition and will resolve if the pills are stopped. Stopping the pill is not necessary, however, because there are other safe alternatives. If the periods are simply very light (1-2 days),you can ignore the problem because this situation poses no threat. If periods have totally stopped or brown spotting like in your case, you have to rule out pregnancy by doing a urine or blood test for hcG. If negative, you may change to a different pill with different hormone in it. This will often lead to recognizable periods because the different hormone is metabolized differently. You can also keep taking the same pill.As long as you otherwise feel well, the absence of periods while taking pill is not known to have any adverse effects. I hope i have answered your query. take care.