My baby weighs 3 pounds, and still some women at the pet store told me "I love Yorkshire terriers! I see you got a toy yorkie probably, because I am gonna buy me a teacup yorkie, they are really small!" I did not know what to say

Some people really take things literly. If a dog is called a"tea-cup size", then he/she is supposed to be able to fit in the tea cup! I guess they do not understand, that the photos they see online, where dogs are sitting in a cup - are just photos of small puppies, and when those puppies grow up, they will be bigger, and would not be able to fit in a cup!
Just ignore comments like that. You know that you have the prettiest, and the smartest babies in the world!
We love them sooooo much, no matter what size or color, or age they are!