I felt just like you, kept flip flopping back and forth about whether to get another one or not. I was so worried Toby, 2, would feel hurt or replaced, maybe I didn't want to go through all the training issues again, what if they didn't get along. Finally we took the plunge and got Lola. I raised 3 male skin kids and Toby is male, so a girl was the logical choice.
We've had her for almost 3 months and it was a very good decision. Toby warmed up to her within a day or two and they're inseparable now. She has a much different personality than him, she's a spitfire, he's more laid back. Training has been hit and miss, just like it was with Toby, but all I have to do is watch them playing together and I know it was the right decision. I do TRY to put bows in her hair but it's still pretty thin and short, so that will take a little longer. I'd have more yorkies if I could convince DH to go along with it!!