In need of some input..

Hello , little background info about what I’m going through rn. I had started to look into birth control at the beginning of march, my insurance only covered the depo shot so my options were limited. Decided to go for it, it was my first time ever on any contraceptive. Got the shot around mid/end of march. I’m anemic so I was trying to find a way to stop my periods, however after that my period lasted 2 weeks the 3 months after that plus it heavily flared up my depression so for those reasons I decided not to continue the shot and since then have not been on any other contraceptives. So here’s the kick. My last menstrual was from June 24th to July 1st, then had some light pinkish spotting on July 24th and have seen no sign of my period since. I understand my hormones could be off because of the shot but I’m not understanding how I had my period the whole time the shot was in my system and now that I’m not on it there’s no sign of my period coming. I took a test 2 weeks ago to rule out pregnancy and it was negative.