OPK Question


So I have been doing OPKs this cycle because we have been unsuccessfully this far in TTC. Yesterday the test line was the darkest it's been but I thought it still wasn't as dark as the control but today it seems to be lighter than yesterday. Does this mean that yesterday was my surge or that I haven't had my surge yet? See the pic. The one on the left is yesterday's and the one on the right is from today. Any advice would be appreciated. I have never used OPKs before.