The GPS GS is quite a comfort once you are on final approach (assuming you are into wind) as it should understate your airspeed. Which is good for not stalling, though less helpful for flap extension.
The only time it happened to me, my mate in P2 called out the groundspeeds, while I flew visually. If he hadn't been there, I think I would have ignored the GPS. The horizon and the aiming point are the most useful references.
The other thing I found useful was (on downwind) to really positively choose the spot on the ground where I wanted to be 500' agl, lined up with the runway, with a standard throttle setting for descent.
Anyhow, well done for staying calm and landing safely.