I have iregular period i had spotting last month and brown discharges last month but this month i start my period reall havy is tht normal?

Probably normal : It sounds like you are having breakthrough bleeding/ spotting (the brown blood), while taking the birth control pill. This happens if you forget to take them daily. You don't ovulate on the pill, so no one ever has a "period" while on the pill. Bleeding that occurs on placebo pills is a "withdrawal bleed". If you try continuous cycling you can stop all bleeding, which is safe and expected.