What's going on?!

Laura
I've been TTC since last August. Miscarried in December. Glow says AF was due last Friday (7 days ago), Ovia says AF was due on Tuesday (4 days ago), she's still not made an appearance. I'm never late. 
My boobs are sore, my cervical fluid has been thick for way over a week and my BBT has stayed reasonably high. I've had bad headaches, weird feelings in my stomach, a couple of days where I've felt sick yet I've had 3 negative tests. 
I did a clear blue digital on Sunday, tescos own brand on Thursday and first response today and they're all negative! Not even a flicker of what could be a faint line. 
What's going on?! 😞 please can someone help me?