Possible to ovulate 7 days after period started?!

I got off my birth control 3 months ago and started TTC right away. I know my body is still trying to regulate but the first month off I got the egg white CM. second and third month I had none. Now I just literally finished my 3rd period since coming off birth control its my 7th day and I have these crazy ovulation pains! Went to the bathroom and there it was all the egg white mucus all over my panties! How is it possible to ovulate only 7 days after ? My periods 31 day cycle! I'm so confused and now not sure what's going on with my body and when I'm even actually ovulating to try and conceive ! Anyone else have this ?!