I am about 3 days late, with more frequent urination. But i got a negative hpt. Could I still be pregnant?

I am trying to conceive and pray that I am in fact pregnant. I always have a normal, on time 28 day cycle but this month..nothing. I have noticed a couple more trips to the bathroom, slight cramping and a couple really bad headaches lately. Please help me with any suggestions, when I can retest, or any similar experiences that you may have had. Thanks for your help!