Well if you are ovulating then you're not pregnant.... yet. Yeast infection would result in a foul discharge, maybe even pain. The thing about yeast infection, though, is that some women do not even show symptoms and a lot of time it goes undetected and untreated. There are these new tests that you can buy at the drug store that can tell you if you do have a yeast infection or not.
Constipation is the infrequency of stools and they tend to be hard, round pebbles. If you're experiencing that is CAN be a sign of pregnancy as a hormone is released during pregnancy that relaxes the bowels making it more difficult to have a bowel movement. Drink more water!
First step I think would be to buy a box of yeast test strips AND a box of First Response pregnancy tests. You need to know if you are pregnant AND have a yeast infection as untreated infections can lead to problems. For constipation eat more fiber and drink tons of water.
PS You can test for pregnancy when your period is due or late, though First Response can detect pregnancy a few days before your missed period. Good luck! Let us know the result.