Irregular periods

I was on the depo for about 2 years, I have been off it for about 8 months now. Since then my husband and I have been TTC. But I've been having such irregular periods. I've talked with my doctor and she said I should be back to normal by now. I have a 3 day period about every other week. It's starting to get really annoying and expensive!! Should I be worried? Please help!