Depo sex lol

Okay so I had my son on 9/11/2018. Well I started having sex no long after I had him because when I left the hospital I asked my doctor and she said as long as I wasn’t in pain, so of course I was like hell yeah. Well I had my first period since having him on 10/21/2018 and that ended 10/25/2018. I’ve have unprotected sex everyday using the pull out method (yes I know you can get pregnant using the pull out method don’t bitch at me about that). My question is I went to the doctor yesterday (11/2/2018) and got a negative pregnancy test, so they gave me the depo shot to have birth control until I get my IUD, is there anyway possible I could be pregnant even though I got a negative test? If I am would the depo do anything to the fetus? My periods are so out of whack because of the fact I just had a baby that I don’t even know like... when to test 🤦🏻‍♀️. NO NEGATIVE OPINIONS ONLY HELPFUL STATEMENTS PLEASE.