Does this sound like pregnancy?

My cycle starts around the same time on the 16th of every month like clockwork.My last period was 3-16-08, it's now 4-21-08 and I still haven't had my period, they usually last only 4 days,so I should be done with it by now.A week or so after my last period I woke up with intense nausea all day long, couldnt eat or drink anything but water,next day I was fine.I've stayed fatigued since then.I've been really bloated feeling,can't even fit my stomach in my jeans anymore.I've been having a lot of white discharge(no signs of infection),really sore , and mid and lower back pain for about a week and a half to where I can't get comfortable no matter how hard I try,also my insides are somewhat tender during ,my husband and I have been having to take it easy.I haven't had any bleeding,but during the time my period was due,the first couple of days the discharge had a very very light brown tint. I took one test on the 17th-pos and double checked on 18th-neg. I'm not sure what to think.