I am not a doctor, but one thing my doctor has told me is that the female body will not menstruate if there is less than 10% body fat. 5'3" and 115 pounds, I don't know for sure how to find exact body fat measurement, but it sounds possible you just don't have enough fat on you. A lot of what you're seeing on your belly could be bloating, or untoned muscle. On paleo you by no means have to have coconut oil if that concerns you, there are other fatty oils you could use. It also sounds like you might not be getting enough carbs; I don't know if you eat tubors or a lot of fruit, but it sounds to me like your body is saying "I am starving, I could not possibly sustain a pregnancy, therefore I will not ovulate."
Stumbled into Primal due to food allergies, and subsequent elimination of non-primal foods.
Start Gluten-Free/Soy-Free: December 2012; start weight 158lbs, Ladies size 6
Start Primal: March 2013, start weight 150lbs, Ladies size 6
Current: 132lbs, Ladies size 2
26lbs lost since cutting the crap.