Last two periods were light than normal. in between the two periods i had light bleeding for a few days as well. on birth control, tested negative for pregnancy, health problem?

Light "periods" ?'s: At 22, stress from work, school, heavy exercise or emotional stress can inhibit ovulation and delay "normal" menstrual events. If your "birth control" happens to be depo-progesterone shots, or a progesterone type of birth control like Nexplanon, these events are common. If not, ask your gyn about polycystic ovarian syndrome (PCOS), which can cause the same effect.