Aw, don't feel bad because your yorkie is porky.
They are so small that even a tiny little bit of weight adds up.
kalina82 lists a good method for determining whether your pet is overweight. Other methods are: look at your pet from the side. The stomach should be higher than the ribs (may be hard to tell if there is a lot of fur).
You can also run your hand along your yorkie's side. The ribs should not be sticking out, but you should be able to feel them easily.
Pets are cute even if they need more exercise.
