Just my opinion here, but from what I have learned, once you dtd, the sperm get to where they are supposed to go, no matter what you do. They stay in the cervical mucous and I don't think any activity is really going to affect that...
As far as knowing when I am Oing, in the past I have always just gone by cm. Starting last month, I have been charting and this month I added in OPK's early in my cycle. Cramps around your ovary area definitely sounds like a good sign to me!
Hope you get your BFP quickly!