CM - hard to work out if CM or you know what

Becky
Hi 
This is my 3rd cycle / fertile window with Glow & since TTC #1 ever!!!! (I'm 30 & HB 37).
Been tracking my temp and OPK and should OV on 27th or 28th Aug. AF due 11th Sept. 
Wanted to attempt to look at CM and thought it was quite dry before fertile window. So now we are BDing obviously more going on in there so I can't really tell scars CM or cum?!?!?! Appologies!!! 
Anyone else unsure?