Hi Shannon! There have already been very good answers/suggestions but I would like to share an experience which we had. My Toto was 1 1/2 lbs. when we brought her home at 16 weeks. Her adult weight "guesstimate" was about 3 lbs., which was fine but we, like you, were so madly in love with her we didn't care if she grew the size of a St. Bernard!
Her weight at 8 months was only 2 lbs. and she was well over a year before she weighed 3 lbs. After a couple more years she began to seem a little "fat" to us so I made it a point to have her checked by her vet in Alabama who "specializes" in the Yorkie breed. She had always cautioned me that she didn't need to weigh over 3 - 3 1/2 lbs. We just never, ever dreamed that she would ever be really fat. She
was fat ... tipping the scales at about 6 lbs.!
I almost fainted!
And ... got a chewing out like you wouldn't believe!! She explained that it wasn't so bad right then but could possibly present health problems as Toto got older. We dramatically cut the quantity of food and I threatened Patrick with death if he ever let her beg a snack from him again! [He's a pushover!
] We were able to trim a lb. or so off her but a year or so later found that her weight was creeping back up. Late one night, Patrick reached down and picked her up and she literally "screamed" to the top of her lungs! We could find nothing visibily wrong and I waited and rushed her to her Colorado vet early the next morning. It seems that her bone structure is so tiny, it can't support the weight she had gained. Five of her little ribs had separated! She had to take an anti-inflamatory and pain medication until they healed and we had to cut her food intake, yet again. She is fine and healthy now but we are daily fighting her little "battle of the bulge"!
I'm sorry that this is so long, but just wanted to say that sometimes Yorkie babies are just teeny. Even though it doesn't matter to
us if they are tiny or teapots we have to do whats best for them. If I were you, I would talk to my vet about your babies' size and skeletal structure and let him/her recommend quantity of food, etc. I wish I could "freefeed" Toto but I can't ... she would probably explode!
Good luck with your baby and please keep us updated.