What Causes Dark Areolas And Irregular Period While HPT Is Negative?

Dark areolas and very noticeable veins on and around nipples. I'm on cycle day 70 my period is extremely irregular and I've been having some random cramping as well as round ligament pains. I took a pregnancy test but everyone is negative. I need to know what is going on. Is it possible I am pregnant and it's still to early. I've been told my cycles aren't regular enough to get pregnant. Oh and the smell of some meets make me sick and sometimes when I eat I get nauseas and bad acid reflux. Thought I had a postive opk on the 1-17-15 or maybe 1-20-15. I've had weird opks before. I only take them when my periods are really late.