Checking and knowing the difference of your CM. Internal testing where you feel inside for your cervix to know if you're in your ovulation period. BBT charts, watching your temperature for your "peak" rise indicating ovulation. Feeling ovulation cramps (if they happen, not everyone will feel them) usually a pain in your ovary (i usually feel it on the right side). And of course the ovulation test kits and such like you have tried already.
you can watch all these things (maybe there is more that i have not listed!) to try and determine when you ovulate.
As for when ovulation has ended...i really am not sure, but usually it is like a 24 hour period from once the egg drops into your tubes. I can't really say if you can determine the EXACT time an egg will drop (other than 'during ovulation")...but you have about a day after that has happened for a sperm to catch that egg!!
Good luck sweetie
