Hello and welcome to EmpowHer,
Since you took the pills correctly, you did not conceive. So you do not need to worry about pregnancy. The vaginal bleeding you experienced was a normal side effect of the pill. The hormones in the pill can also disrupt your regular menstrual cycle. Your period is not irregular due to pregnancy, but because of taking the pill. You can also experience side effects including: nausea, tender breasts, and cramping.
Your regular period will return to normal soon.