Hi AndrewMcd.
I had a hard working student a long time ago who for some strange reason couldn't fly a nice approach and couldn't land. It was very frustrating for both of us until we discovered why...
We suddenly realised that on final and in the flair, due to the different attitude of the aircraft flying at lower speeds he couldn't actually see the runway. Raising his seat slightly completely changed his future!
Since he'd been trying to land blind for so long, landing when he could see was a piece of cake
Maybe worth a try if you're struggling at all.