Am I pregnant ?

I took a hpt Saturday and it was negative and a few hours later I checked again and there was a blue plus sign. I read about evap lines and it said they can usually be grey or colourless, this one is blue.. So I took another one Sunday, pink dye, and negative and another Monday, blue dye, and negative as well. My period was due Thursday but it was very little and brown spotting. Any opinions, advice or past stories ??