want to know Im I pregnant

Hi, Im 26 years old and got married in july 2010 and had a miscarraige in the month of october 2010 . since then we were having protected sex because of my studies and also my menses cycle changed to 37 days( earlier it was 30 days exactly) . finally know we are planning to have a baby, but during this month i had a light spotting on my tissue once in a week and i had headace too and also morning sickness. are these the signs of pregnancy? but  today i had a home pregnancy test  and found negative result . my date was on 17th april and i took test on 23 early morning . is there any chances of getting positive resul t? should i wait fr few more days ? and i wanna know what could be the reason for this spotting. and also i wanna know having frequently sex will effect the pregnancy?whta measures should i take plzz help!!!