I agree, although annoying ...it is quite normal and may take up to a year to regulate completely. If it is really bothersome or you are ttc again, make an appointment with your doc as there are things he can prescribe or advise.
I'm having the same thing, it's all normal. I had 2 periods in 3 weeks, and then nothing for 50 days, so don't worry. just be cautious though ;)
However I haven't stopped breastfeeding, but it happens differently for everyone. Some of my friends only had it come back to normal after quite a few months