Am I Pregnant??

Okay so here it goes....I really haven't been tracking ovulation or anything. My fiance and I have been trying to conceive for the past year. My periods are regular and they happen around the 29-30th of every month. On the 20th I experienced some brown stuff in my underwear and when I wiped. I took a pregnancy test this morning and it told me I was negative? Was it too early to test or what?? I am experiencing extreme headaches, I feel a little bit nauseous, and I am urinating constantly it seems???

Please Help!!!!