First response early pregnancy test! How accurate?

So, me and my husband have been trying to get pregnant for about 5 months now. We are both in their mid 20s and no luck yet:( I've been tracking my period, ovulation, bbt. This month the first time i just had that feeling that i got pregnant. A few days ago i started to have migraines, i'm thirsty and sleepy all the time and i have to go to the bathroom A LOT! Of course i know these can be symptoms of a bunch of other stuff:( So my period is due in 2 days. 4 days ago i tested with first response, negative. Yesterday i tested again, negative. Yesterday i had a little bleeding, but so little, that i wouldn't have noticed it if we didn't have sex. No blood since yesterday, no cramping! Could i still be pregnant even though i got 2 negatives? Have you ever tested negative when you were pregnant? Thank you!!!