I'm 17 days late for my period negative home pregnancy test my cycle is regular lower back pain and cramps in lower stomach from time to time?

2nd HPT in order: A 2nd HTP done 2 weeks after the first may be revealing. Otherwise, you should consider an appointment with your OB/GYN doctor. As a precaution or until you can verify your pregnancy status you should immediately cease from lifestyle habits and/or use of potentially offensive prescription drugs (as well as illicit if applicable) which your primary doctor can assist you in identifying.

Not sure: if you are late on your menstrual cycle and you are normally regular and urine pregnancy test was negative you may want to see your family doctor or OB/GYN to perform a blood test and check for other possible causes