Ovulation cramps but no LHsurge yet. Is this normal?!

Rebecca • 36yrs old, pregnant with my first and my SO's 3rd 💕💫
Hi ladies. I'm TTC for baby#1 at 36. My SO has 2 children all ready so it's been a bit of a road to getting him on side with having one more! But we are there now and in our first month of trying!! 
I'm taking it all pretty seriously, I want to get to know my body really well, and hopefully, baby dust willing, will be looking at a BFP in the not to distance future!
So, I've been tracking my first cycle on Glow and also using OPKs, so far no surge but Glow reckons today is ovulation day, and I've been cramping all day. I tested this morning and this evening, both negative and all have been exactly the same level of lightness. Can someone tell me, will my OPK literally turn matching dark line overnight, or would it gradually get darker each day? I'm starting to freak out that I can't ovulate properly as this is the first month I am using the OPK tests. But then again I am getting cramps so could it be I am ovulating and the tests just aren't picking up the LH in my pee?? We BD'd Friday and Sunday anyway so hopefully if anything  is going on we are in the zone, but im still just nervous that something could be wrong, why no LH +ve for me yet?? 
Any ideas or thoughts would be really appreciated, baby dust to you all! ✨💫😊