weird periods?!

I'm 15, and my periods are always irregular. It's October currently and I still haven't had my period, last month (September) it was on the 26th and was super super heavy. The month prior to that it was in the 23... it seems to be getting more regular, but today is the 25... and no signs of my period? I typically don't get signs before I start my period anyway. It just kind of happens...