Birth control and periods.

I had a baby 3 months ago and got the shot before leaving the hospital, well long story short I couldn’t stop bleeding due to the shot and they gave me estrogen to stop it, now I’m on the pill and it’s time for my period but the doctor said who knows when I’ll bleed again.. anyone else had this and when did you start having a normal period again? I take it correctly but I’m still worried because no period for me always makes me worry about being pregnant again.