Birth Control (pregnancy scare)

I just experienced the craziest moment today. So I had my first depo shot on April 2 2017 and didn't continue it 3 months later. In July I had my regular cycle and I missed my period for the month of August and September. I've taken three pregnancy test which all came back negative. I decided to visit a family planning center to have a pregnancy test + ultrasound done. Come to find out I'm not even pregnant. I've been stressing this whole time. I was actually ready to get the news of being pregnant. I guess it's not my time yet, also I'm starting my birth control pills tomorrow 😊