Hello,
Welcome to ehealthforum.
The symptoms that you are having could indicate pregnancy. The usual urine pregnancy test done at this time could give a false negative result (negative test even though you are pregnant) due to less concentration of pregnancy hormone (HCG) in urine.
Do not ignore the symptoms especially the cramps; meet your gynecologist and request to get an ultrasound scan and blood beta HCG test done to confirm pregnancy.
All the best.