I suggest you buy a Wahl peanut trimmer ($40-$50 @ Sally's Beauty supply), a grooming table ($35 @Petedge), some scissors ($25 on sale now @ Petedge), and a Yorkie grooming video ($25 on eBay), and you'll be in business. I'm sure you already have all the combs and brushes you need. Your puppy will never have a bad hair cut again, and think of all the money you'll save over the lifetime of your dog.
My groomer is my best friend, and she does a wonderful job grooming my dog. But it is just so easy for me to groom my yorkie to suit myself every week after he gets his bath. I just finished trimming him an hour ago and he looks GREAT. I'm so glad I finally invested in the little grooming table. It makes it a breeze to groom him.
The video I bought on eBay shows how to do the puppy cut AKA teddy bear cut, the schnauzer cut, and the long "show style" trim. It goes over everything step by step and teaches you everything you need to know. I watched it twice before I started grooming my dog. It is really helpful. I know if I can groom my dog and make him look good, ANYONE can.
Good luck to you. I hope your baby's hair grows back soon. She is adorable.