period late, not sure why...

Which should be fine, given that there is still a bit of time before this can actually be called a problem (and maybe this is all just paranoia), but i've already been through a lot of the symptoms (sadness so deep you could drown in it, like you could drown in period blood, and cramps that had me lying in a dark room with only a hot wheat pack for company), which would usually be followed by a bloody mess, but nothing really happened, and i'm feeling pretty normal now. 

I'm also pretty sure i'm not pregnant. I've done two tests so far (planning on doing a third), and both of these came up negative (one line). 

Anyways, there's almost no reason for suspicion. When having sex, my partner has never ejaculated inside of me without a condom on. And i haven't noticed any breakages or malfunctions there...

So i'm just wondering what's going on. I'm 15, and i haven't been having periods for many years now, so i don't really have much to reference this off, but does all this sound normal? And if not, is there a chance that i could be pregnant?