Aww, congrats on your new addition! Post pix of her if you can
All I really know about size & age is that for yorkies, it can vary considerably. I'd take a look at her parents if you can, to get an idea of her adult look & size. If you're trying to see approximately how big she'll grow to as an adult, google the yorkie growth chart.
My puppy, Billi is another "little". She's 2.6 lbs at 6 1/2 months... Tinier than we ever imagined. She's the love of our lives, but she comes with hew own set of rules, like no jumping off furniture (we made her ramps for the couch/bed) and she doesn't ever go outside unattended, we have to watch her like a hawk when she plays with other dogs because she could easily get hurt, etc... But these little ones are well worth the extra effort, I think.
Welcome to YT!