hi

my last period was 21st-26th feb 2010, i had sex on 2nd march 2010 without using contraception.
on 12th april(this month) i thought i was getting my period as i had brown spotting, this has been happening on a daily basis ever since(13days so far) not enough to justify a tampon/towel. some days it only happens when i wipe. i have done 2 tests and they were negative.
can anyone help me i need to know what is going on, i cannot get into see my doctor for over a week and i am going out next week and am worried about drinking if i could be pregnant.