I'm 14 and have had protected sex with my boyfriend 3 times. I'm the only person he has had sex with and says he has gotten tested for STD's before and he was negative. I trust him. But I've always had discharge. I think I first started getting it in 4th grade, but lately I have noticed that my discharge is like a light yellow and has an odor. I have no pain urinating by the way. I'm supposed to get my period sometime this week. Is this a sign it maybe coming? I notice during class my underwear feels wet so I check it out and there's yellow marks in the lining. I read somewhere the discharge can turn yellow due to air. Help?