Depo does not regulate the menstrual cycle, I am surprised any doctor told you that..

The pill, patch, and the ring would regulate your periods.

You can go on another bc type now, even though you are bleeding from depo. A new bc type would also help to stop the bleeding.

You are at risk for pregnancy though.

Like cari said, depo does not regulate your period. It usually gets rid of your period altogether, but it doesn't do it right away. Many women have a really long and crazy period right when they start depo and when they get off it while their bodies adjust to the hormones. Even four weeks of bleeding is not uncommon when starting or stopping depo.

Your doctor should explain all of these things to you before starting a hormonal birth control. If you doctor is giving you things without talking about what they will do to your body, what the side effects are, whatever, you might want to look for a new doctor.