What Are The Side Effects Depo Provera?

Hi, I'm 28 years old...overweight but healthy ( I think). My problem is I was on the depo provera birth control injection for almost 10 years. I stopped getting the injection and have been off of it now for about 6 months. I never got my period while on birth control. Recently I got my first period since being off the birth control. It lasted 3 weeks, at first the flow was regular, then heavy, then normal to light. I didn't have my period for about 1.5-2 weeks. I had my period again now for about 1.5 weeks. The flow is what I would describe as very heavy with a lot of blood clots in it. Is this normal? Do I be worried? When I was younger I never had a heavy flow. I get cramps now and I never use to. I know the last time I got my period was over 10 years ago and things can change but the heaviness of the flow is worrying me. I feel weak sometimes.