Hi,
I'm 28 and my partner is 36, we stopped using contraception a few months ago.
However, I'm not sure if I am ovulating. I bought some OPK strips and have been testing when I thought I was ovulating.
On month three now, I never seem to get a dark line...
The line has appeared variably, but it's usually quite faint 
The thing is, I have a very regular period every month. I'm on around a 26-28 day cycle currently, according to my app.
I usually get some brown discharge/blood before my period starts for a few days and I also have pain and cramping for a few days before my period starts too.
My periods are very clotty (tmi) and very painful on day one and two, especially during the night - so I can't rarely sleep through the pain, I get horrid leg and pelvic cramps
then the pain eases off and the rest of my period is pain free.
I'm supposed to be ovulating at the moment, but, a few days after my period ended, I realised I had some stringy CM. When pulling it between finger and thumb (sorry, tmi) it stretched a little way before breaking.
I also had very heavy boobs around this time.
I've been taking pre conception vitamins with folic acid for the past month.
We've been having sex at least once a day! 
I think I might have PCOS or Endo, or maybe both. Never been tested as I'm scared of anything medical (health anxiety) and especially any intrusive checks, e.g vaginal.
If anyone can help, that would be great 