Need Help fast!!!?

my last period was 28th march and i ovulated late on the 16,17,18th april we ttc on the 18th... so far no period, felling a litle sick, slightly sore 's,period pain on and off for the last 2 wks but no period, i did a test about a week ago and it was neg and i just done another and it was neg aswell, also when i went to the toilet before there was clear dischanrge with a tiny few streaks of brown blood... with the preg test i went to the toilet then about 15 minutes later i done another wee and used that urine for the test could that be why im getting neg result as im not waiting long enough for my urine to get enough hcg in it, sorry to be so confusing but im going crazy here