Well first of all I dont think that you should get another puppy, I mean you are finding it very diffucult already with the 1 you already have. cOuld you imagine having 2 unruly puppys. First of all my first yorkie was 6mts when I got her, when I tried to pet her, she constantly bit my hands, this was also very fustrating for me also, but I constantly pulled my hands away and kept repeating a strong NO. Beleive me it took a while, but she soon got the message. She is now an adorable and affectionate girl. Also my 7mt old Betty did the same, now she very rarly does this. I used the same method as I did with Missy. Look maybe if you have the time you should bring him to puppy classes, this will help you a great deal, I think. Also beleive me yorkie puppys are so full of life and energy, they can be hard work. And beleive it or not, they tend to calm down when they reach adulthood.
Hopefully you will get a lot of help here, and try not to worry. YOu can always come back here and ask whatever you like. Thats what we are here for.
__________________  Missy Boots Betty |