I don't think you can use a ratio to make the douches. I think you have to make it to a desired pH level. From memory, anything under a 4 will kill off the sperm.
Sweets - That CM I think would be ideal - boys won't like that. If you will have trouble DTD with that CM, maybe try Sylk which is a lube with a pH of 4. The Sudafed is also designed to dry everything out too. I think the Replens is supposed to be used after DTD (but not entirely sure). I think Refresh is the one you can use as a lube. Check out the FAQ's though just in case I'm wrong.
My AF came today so it turns out that I may O on 1 August or 3 August (depends what my usually regular cycle would like to do this month).
Re the supplements, I didn't find any difference once I started taking the supps. Not sure if it would affect you because of your other meds though. Instead of taking cranberry supps, you could try and drink the juice. That has a pH of under 2 (I tested it the other day).