did not know about calendar but her sudden mood change was a dead give away lolNot yet, it's best you wait if you're after vaginal sex. I'll add it to the tags myself once that (future) update hits public release.
Yes, there already is a calendar that you can use to track her period and it will calculate her theoretical ovulation days.
you know when you have lived with a woman to long when you run for the hills on random mood swings ^_-