Thank you for all the information!!!
I don't think I'm going to spay my girl for quite a while, because I might want her to have puppies...haven't decided yet.
It's just that yorkies are so small and Greece is so over-populated that if I lose her I'll probably never find her again! So chipping her is a good idea...
But even the needle from her shots hurt her a lot, she was crying and whining for 10 minutes after, really loudly! If this one is bigger she'll be in more pain!!!