Nope. If your period is really regular and predictable, you are almost always ovulating about 14 days before your period starts. Sometimes though, even if you are dead-on regular, having a period every 26 or 28 or even 35 days, you can have a cycle or two where your ovary doesn't quite get the job done and no egg pops out. When you don't ovulate, you will usually still have a period. But, if you're typically plagued by cramps, you won't have them nearly as badly the months you don't ovulate. Some women actually feel it when they ovulate and have a sharp pain on the lower left or right side (depending on which side is ovulating) and some women even have a little spotting. Don't assume that just because you normally feel ovulation, but didn't one time that you haven't ovulated! Assume that every single month you ovulate and use protection if you are sexually active. I have never had regular periods and women like me have lots of cycles where we don't ovulate, but we can't count on it either!