Whoops - I should have said "No the Biewer is not a mix with a yorkie and a maltese. It is from a breeding of two
Yorkshire Terriers that carried the piebald recessive gene. They are Yorkies. You can go to the BYTNC (Biewer Yorkshire Terrier National Club) to read about this breed
http://www.bytnc.org/
I would like to see a full body picture of your little one. If you go to the above website you can see the standard of what a Biewer should look like along with pictures of some of the Biewers here in the US. Who was your breeder? If she told you it was a Yorkie and a Maltese then she was wrong and if this is what she breed together then you do not have a Biewer.
Your little one could be but just a face picture doesn't show enough of the dog, did she provide you with a pedigree? Can you post it?