help! depo shot

hi i have an almost 3 month old and was back on my pill 2 or so weeks after birth but recently just over a week ago i got the depo shot as i was going to get the implant but there’s a long wait where i am so decided to go with the injection instead. they said that i was safe to have sex whenever, due to the pill i was on, that when i had the injection there was no gap in my protection, they overlapped meaning that i wouldn’t be left unprotected while switching contraception. i was due to be on my period this week but i haven’t started and haven’t had any of the brown discharge or spotting i got told to expect after the injection. is this normal?