Katie34... I believe you are correct, EWCM can lesson as we age.
But, there are many ways for you to combat that. You can try herbs like Vitex or Soy Isoflavones (these also help bring on ovulation). You could also try medications that create mucous such as Robitussin or Musinex. Or, you could use real egg whites or Preseed as lubricants during intercourse.
With your long cycles, I would recommend that you look into the Vitex or Soy, since these can help with that as well.
As for when you O? I agree that if you are O'ing, it is more likely around cd21-cd22.
Temping and/or using OPKs can help you find that out.
I'm no expert! So be sure to research before you decide to use anything I suggested.
43 w/Emphysema - TTC from 2005 - 2013. 2 miscarriages in 2008. Good things do not come to those who wait.