Dizziness, passing out, missed period and negative pregnancy test.

Dizziness, passing out, missed period and negative pregnancy test.

I am 19 years old, started my period at 14. It has always been the same way, never had changed. I get it 5 days early every month and usually lasts from 5-7 days, usually 6. Sometimes I get it twice a month, it just so happens this was supposed to be that month. In October I got my period on the 9th, in November I got it on the 4th and I was supposed to get it again on the 29th because of the fact that I always get it 5 days early. Turns out it never showed up. On the morning of the 29th everything was going good until I started getting hot flashes while I was sitting. Then when I was standing I started feeling dizzy and everything started turning white and really blurry. I was in the laundry room at a friends house and all I remember and reaching over to lean on it and just like bam falling. My boyfriend suggested in buying a pregnancy test because of the fact that my period didn't show as usual and well because of the fact of what just had happened. Before he left to work we went into the pharmacy and bought one, went back home, took it and it came out negative. I'm wondering if something is wrong with me. I know I should have went to the doctors but at the moment I thought it might of been that I was pregnant. I made an appointment to visit the doctor Monday morning but I at least want a heads up on what can be going on just so I can relax a little and not be so anxious the whole weekend. Please some respond. I need answers. We are really worried that it can be something serious.