It sounds like you could be ovulating around now. You're right at the point of your cycle where that could happen. I always got cramps and lower backaches before ovulation as well as extreme fatigue some cycles.

If you have already ovulated, the symptoms you are having could be due to the progesterone released right after ovulation and only possibly early pregnancy signs. I did not have any signs or symptoms of pregnancy until I missed my period. It usually takes around 7-10 days after ovulation for the fertilized egg to implant, and then your body will start producing HCG, the pregnancy hormone and that is when symptoms can begin (though it is rare to have symptoms so early). During my cycles, I often got constipated after ovulation, even before I was trying to conceive. Now, I'm always constipated (I'm about 11 weeks pregnant), but I think it's due to the iron in my prenatal vitamin more than pregnancy.

All you can do is wait and test if your period is late.