HI!
melon3 Is correct. Save your strips for the next cycle. Optimal frequency of intercourse is daily or every other day. That should assure that sperm are present when the egg is released which is what you are trying for. DON'T have intercourse MORE than once per day though, because that can reduce the sperm count and doesn't improve your odds any. If you are a mother you probably don't have time anyway! ;)
Good luck!
Dr B
I also use OPK, but I use the digital ones. Once you have detected your lh surge, they say you are most fertile on that day and the day after. They also say there is no need to test again once you have found it that cycle. You did right to have sex both days. Good luck and I hope this has helped.