I'll tell you I am older, in my 40s and just learned this, and have been monitoring myself, and its around 10-14 days after your period that you are likely ovulating. Its when your egg(s) are released. Its mid month and if I was guessing I would say that, but you can ask your doc too. When I was about your age and into my 20s, I would be spotting too at times mid way.