Been trying to conceive,5days late with period?

me and my fiance has been trying to conceive for 15 months now,im 18,and i do have metabolic syndrome,which PCOS is KNOWN to go along with metabolic syndrome.but i usualy have regular cycles,this month my period was due on the 14th its now 5 days late (the 19th today) and for a week now ive been having diahreaha still have it right now,i've been having such bad cramps and stomach pain to were it wakes me up when im sleeping,feel like im goin to throw up sometimes but dont,and i've tookin a few pregnancy test but their ALL comming back NEGATIVE, could i be pregnant??or does anyone know what is goin on??i tryed to see if i could get a pregnancy blood test but they need a doctors note,im not sure how to get that across my doctor do i just ask him??anyways i really want my little baby soon so please help!! and good advice to me about conceiving incase im not pregnant,thanks so much!