depo provera? period? im confused.?

[mJaden'sMommym]

So I got the depot shot on12/18/08 and started bleeding for 3 weeks on 12/27/08 due to the depot shot. I've been cramping ever since saturday(i had sex with my boyfriend for the first time since i delivered). Now a few minutes ago I realized that I'm bleeding, so I'm guessing it's my period. I thought the shot was supposed to delay your periods, make them irregular, and/or make them completely stop. Has anyone had their period on depo? and if so, were they irregular?
*I'm planning on switching to The Pill also.
feel free to email me.