Day 14 Post sex negative but symptoms

I'm so confused considering I didn't have sex during my supposed time of ovulation so it's hard working out the time.. I was a week or so away from getting my period. Tested today two weeks after sex. Negative Ive been having mild cramping pretty much everyday and more so at night. I have been getting looser bowel movement. But I'm told constipation is more common. I'm laying down at the moment and have a sharper pain on my left side. It's driving me crazy about if I am pregnant or not. It predicts my next period after my missed one (6 days delayed) would be 28th April. I never miss a month of no period. Shall I test on 17th or try hold out til 21st April?