I'm no expert but i'm pretty in tune with my body so will tell you what i've noticed. Last month i had little niggles low down, bd'ing seemed to make it worse, kind of like sore muscles down there and the day after bd'ing I had a pain in my side that lasted all day.
This month I am paying way more attention and the day I entered my fertile period, I had a bad headache, CM went from dry to creamy/tacky on pants to a little EWCM at night, the following day again at night I had lots of watery, jelly like CM and feel extra wet when BD'ing. I also have occasional cramping which is not painful and does not last long, under a minute and comes in waves at random periods.
I don't think I have actually ovulated yet but I am definatley on the lead up to it and CM has been my biggest sign, will be watching closely for the sore muscle/pain down below and the CM to dry up/change and i'll know Ov has happened.
Hope this helps xx