Depo..confusion.

Monique
Hello everyone.
​I got on the depo shot in the beginning of June. I came on my cycle regularly June and July. I was suppose to go back and get my next shot at the end of August, but I couldn't make it due to my work schedule. I haven't had a period in August or this month?? Has this happened to anyone else? What could this be? Please help. 
​Thanks In advance