Depo is typically given once every 3 months for birth control
because it has a 90 day therapeutic range.
If you got the shot 2 times (at the beginning and 3 months later) you were covered for 6months.Then most women will ovulate and have a period in the 90 days after the last shot's therapeutic range. For example, #1 shot sept 1st, #2 shot dec 1st, then expect a period mar-may. Some start later.