Awww...congratulations! If that's him in your avatar, he's a doll. He'll change colors for a while, but you'll have to wait to see what his final colors will be. It's a Yorkie surprise!
Eight (8) weeks is really young...too young to worry that he's not potty trained or worry about him 'slipping' on one component of growing up while he's learning so many others, too. Just hang in there and be patient and consistent with him. He'll get there...and you are just going to love that little one.