Have pregnancy sign could i really be pregnant

I am 21 and i think i might be pregnant. I am now into the 5th day of my missed period. I have been experiencing Nausea, Soreness of the Breasts , Been more tried then normal (sleeping more), Some cramping. Been going to the bathroom more then normal, also i have experienced headaches which i normally rarly get.

I have taken 3 at home pregnancy test and they have come up neg. I know one or two people may say i might be stressed and that why my period is late ( i know i am not stressed, i have not reason to be). I would be happy if i am and if i wasn't pregnant. I would like to have a baby, both me and my partner want kids.

Before i forget. My last period (which was about the 5/10/07) was not normal, it was lighter and did not last as long but also i went to the bathroom a couple of days ago and there was a small amount (droplets) of blood on a underwear and nothing when i wiped. Also now there is a small amout of white discharge on my underwear.
we have had sex every day from the 6th to now.

Any type of advice is more then welcome.

thank you