What's going on?

I'm CD30 (which I never have 30day cycles, usually 25-28) and I keep having to push my period day back. And I have lots of watery CM (keep thinking I've started AF). But I have all my normal PMS symptoms, sore breasts, my back is killing me (more then normal), I even had my 1 grumpy day, and my 1 cry all day, days. I took a test this morning and got a BFN. I don't get what's happening :(