What Are The Side Effects Of Using Birth Control Pills?

hi im 21 im on birth control since i have been on it im geting my period two weeks long the first week its a brownish colour and the next week it starts getting normal but its not heavy flow i have been on the pill triphysil but i went off coz i kept forgetting to take it so i went the 3 month injection and im experiencing the same problem with the 2 monyh injection that im on now