I was on the depo shot for about 7 years. I decided to get off because I wanted my body back to normal. It took me 11 months to have my first period.
I know several people who got their period much quicker and those who to longer. Like everyone else has said, it just depends on your body.
Personally, I would not get another shot & use condoms.
Your body will go through changes -- I had severe acne which I had never had-- but I think in the end you will feel better naturally.