Agree! 4 inches is good enough. Forget about surgery.
Concentrate on:
a) foreplay and working her clit masterfuly. Some women are ok with fingers some others with tonge
b) get proficient with 2 or 3 positions (missionary, woman on top, get the idea?) There are some other positions that don't work for me so rather than getting frustated I go for the ones that do
Build up confidence, even though it is easier said than done. Again, forget about surgery!!!