Cramping 18 days after d and c

This is long but please read

Ok so it's been now 18 days after my d and c which I had to remove remaining placenta that didn't come out after I had my baby and Ive been having some cramping and also a bit of lower back pain for the past 3 days nothing unbearable but it's there as for bleeding sometimes I have nothing and other times i have brown spotting

Does this seem normal I thought by now I wouldn't have cramping anymore

I am scared of infection or maybe possibly having some products retained still the dr said he was pretty sure everything came out because the tissue matched exactly the measurement on the ultrasound but I have hypochondria and these pains are freaking me out

I also did get the depo shot for birth control a few days before the procedure so idk if that could be causing the cramps because ive also had bouts of nausea every now and then

We called a dr on call and she said she is pretty sure the pain is possibly from the depo

I did call doctor office today to get an appointment but due to some insurance issues they have to call me back to see if they can see me or not they haven't called me back so now I'm just waiting and very nervous

Has anyone been through a similar situation ??