pregnant?

My period isn't due until the 25th but me and my partner had sex during my 'fertile week' unprotected, I've noticed I have clear discharge even now just before my period as well as creamy white (no smell), the amount varies. And me and my partner has sex twice last night and once this morning and he's saying I'm a lot tighter then I use to be. Could this be a sign? I also have tender nipples but that's a normal pms sysptom. And I've been having like a sharp twinge throbbing feeling (on and off) in the same spot of my lower abdomen for the past 3-5 days which is usuaual. What has anyone else experienced? 
I'm 18.