Period

So my period has been very werid lately ( I’m on birth control the pill going on 2 years now) an it was super light now I normally start after I take my second brown pill an it was like droplets an my periods normally not heavy but their regular periods but I eventually got it an I’m supposed to start today took my second pill have nun happen yet an I’m very confused like I need answers if anyone know anything bout birth control like can it change out of no where or mess up with stress or sum like I’m just confused but if someone could help me I’d appreciate it lmao