After much thought and research
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I wouldn't use this word if you STILL buy a pup at 6 !!!!!!!
weeks.
You can spend about 2 hours ONLY over internet to understand that GOOD breeder will NEVER sell a yorkie at this age. If yorkie is 12 weeks you will know APPX. adult weight.
Sorry, but this is YOUR fault, you shouldn't complain now. Hopefully, your pup is healthy.
Please, all of you who are looking for a pup, educate yourself. It is not difficult.