Thanks for your query,
You had single sex on 13th july. After that you are having your periods regularly plus three pregnancy
tests are also negative. I dont think you are pregnant. For urinary problem ,you can do a urine RE/ME test to exclude urinary tract infection
. Feeling of heart beat is probably pulsation of aorta
. Even in normal pregnancy you can not feel heartbeats of fetus but ofcourse you can feel the movements.
Hope it helps..