If its showing negative then unfortunately all you can do is wait. sorry
Correcting my typo from above^^ that should say I'm now 15 weeks pregnant... instead of I'm not. Sorry
Wait until you've actually missed your period for the week and re-test to be sure. When I was trying I took the first test just a couple days after I should've started my period and the test was negative I waited another week or so and re-tested and it was positive, I'm not 15 weeks pregnant. Also most of the PMS symptoms your talking about are similar to pregnancy symptoms, I had sore breasts and some cramping due to the expanding uterus. I would suggest taking another test in about a week or so. Best of luck!!!