I can almost see the advantage you had. As you know, when you have that
kind of advantage you have to exploit it fast. It's easy to say to yourself
"I've got this killer position and I'll sit on it like a mattress full of
money!". That happened to me once. Against a good player, you know your
initiative on one side will be met by one on the other, so you have to adjust
from being comfortable with a "won" position into being ready to actually win it, which
will involve too much hard thinking.
There was a great game Pillsbury-Tarrasch Hastings 1895, where Pillsbury
got a big advantage in the center in a QGD. His going over to the King side
attack while thwarting Tarrasch on the Queen side is a textbook example of
how to exploit an advantage in the center.