shortened cycle after d&c

I'm on my third cycle since my d&c for a missed miscarriage in March, and it seems to have adopted a new pattern. I was regular as clock work at 28days before, but it seems to be only 23days now. Anyone else had this? How does it effect my ovulation? I thought I got a positive opk during the wk glow suggested but I wasn't testing every day, so now I'm doubting myself.