For most women, ovulation happens on the 14th day of your cycle. That is, two weeks after your last period started and two weeks before your next period is due to start. Of course, every woman is different, and the only way to know for sure when you're ovulating is to do something called Charting and Temping. A good place to find information on how to properly chart and temp is on a website called fertilityfriend.com.
And yes, those can all be pregnancy symptoms, but if you're pretty close to starting your period, you could indeed just be experiencing premenstrual symptoms. I would take a pregnancy test the day of your expected period to get the most accurate result.