I've been on depo for almost a decade. Not non-stop, I went off it for about a year and tried other things and then went back on it.
The "damage" depo does to your body is mostly reversible. People freaked out when depo appeared to hurt bone density, but later studies showed the loss of bone density is reversible once you stop taking depo. Lots of people are terrified of depo and insist it will kill you. I had a doctor years ago REFUSE to give it to me because it was "really bad for teenagers." So I went to a gyno instead and she literally LAUGHED OUT LOUD when I told her that and said "No, actually, depo is better for teenagers than it is for older women!" People are just funny about it (and some other forms of birth control too) - they have their own opinions on stuff based on one study they read somewhere and convince themselves it will kill you if you go on it...
I spotted constantly for the first year I was on depo, then it stopped and I have never bled on depo again. The biggest weight loss of my adult life has occurred while on depo. I only have mood swings if I forget my appointment and miss getting my next injection, which hasn't happened in years. I do take calcium supplements but realistically ANY woman on ANY form of birth control really should be taking calcium supplements.
That said I honestly wouldn't recommend it to anybody who wants kids someday. It can take a long time for your body to go back to normal as far as ovulating goes. And your fertility starts naturally declining a lot sooner than most women think... just not something I would recommend.
crazed, you are probably reacting to the estrogen in most birth control pills and that's where the headaches are coming from... tends to run in families too. Have you ever tried a progesterone based birth control instead? I know there's at least one progesterone pill out there but I can't remember which one it is.
I'm not sure if Nuvaring is progesterone either. I was on Nuvaring for a while, that's initially what I went off depo and switched onto, BUT it's the only birth control I've ever actually had terrible side effects on. Bizarre skin reaction and I got depressed, and got more and more depressed the longer I was on it. It wasn't until one day I was actually googling the skin reaction and happened to read about the depression and it clicked in my head. I immediately went to the bathroom, pulled the Nuvaring out, and never looked back. My mood started improving the day after I took it out. Took a few weeks until I felt "normal" again. I was on it non-stop to treat endometriosis so my body was never getting that break from having it out, or I bet I would have figured it out a lot sooner. =P
But a friend of mine was on Nuvaring for a long time and she really liked it. It's basically the same theory as a pill pack... you put the ring in for three weeks (three weeks of hormone pills) and then you take it out for a week (one week of no/sugar pills) and then you put another one in for three weeks, repeat. So that might be an option for those of you who aren't fans of having to take a pill every day! I really did like it except for those nasty side effects. ;P