My period started with 2 days of brown discharge and then 2 days of heavy normal flow. then, nothing. can that be normal?

Yes, normal: Spotting prior to full flow implies your progesterone levels are dropping (which is normal) and your lining is preparing to let go. Your menstrual cycle pattern can change over the course of your reproductive years. As long as you have full flow bleeding at some point each month then it's normal. If you want your menses to be more consistent then you could always take birth control pills (BCPs).