I don't know about constipation, but with both of my pregnancies I had short periods for several months, I would test and talk with your doctor.
If you have enough hcg hormone in your system to change your eating habits and make you constipated, then a hpt would definitely detect it. Take a test.
My gut feeling says that even though your period was shorter than normal, it was still a period and you are not pg. Constipation during pg does not happen until well after you know you are pg (5,6,7 months along).
About 2 and a half months ago i had sex for the first time and we didnt use any protection. About a week after that i had a yeast infection. I took meds for that and had been fine. I had a regular period. And a month after that i had another regular period but after my period stoped i had lots of brown discharge. I have now had it for 2 weeks. I have also been tired and nauses. I took a pregnancy test and it came back negative. What could be causing this brown discharge?