Nedge85, yes, you are correct that the ramshorn snails did not magically appear because of your feeding habits. They most likely came in hitchhiking on the live plants you introduced to your tank. Snails often hitchhike on live plants.
I think even if you could feed less (I understand you have been feeding very small amounts of food), the ramshorn snails would decrease in population but still not disappear entirely. If you don't want them in your tank, then you will have to remove them. Some people like snails and some people hate snails, including ramshorns. People who like ramshorn snails like that they clean up the tank by eating leftover food, including rotting food; dead, rotting and dying plant matter; and algea. They also like that ramshorn snails will serve as an early warning system of bad water quality when they are all hanging around at the waterline/top edge of the water.
Ramshorn snails are peacefull and will not harm your shrimp. Your shrimp will probably clean the snail's shells by eating algea and bio-film off the shells.