peak opk but line not quite as dark as control

So yesterday I got a Peak on an OPK - cb advanced. However the line did not look to be as dark as it should have been. Maybe almost as dark as the control but definitely not darker. Tested again the next morning (this morning) and it was back to negative, line looked lighter. No rise in temp today. I've never temped before. Anyone ever get a peak opk result and the line just barely as dark as the control? Not sure whether to trust the digital response or eject the stick and look at the line. Seems conflicting. Tested every morning with fmu. 5th month TTC and losing hope:(