Testing twice a day is really the best way to make sure you don't miss the surge. Looks from your pics in the other post that you captured it great though!
I am praying you don't have to buy more next month...because you will have a BFP...but the Answer 20 pack (Around $20) and dip kind...not midstream really work better. Here they sell them at Kmart and Tops supermarket. I think Rite Aid sells them too. I was too late in posting before you bought them. Of all the brands I have tried they show the darkest positive. It's also nice to have 20 to use and not worry about wasting them.
Anyways...get BDing! After you see the surge you will usually O within 72 hours if I remember right