You probably didn't do anything wrong per se.
Big dogs who are protective have the size and equipment to do damage.
I would guess that pugged just really got his adrenalin going somehow and it was bigger than she could handle. You were between her and the "problem" so you got the end of the K9s.
Hope all is well now. Is she obedience trained? That is often the best way to get in control of big dogs.
Sorry this happened -- but don't think we have to worry about who is going to protect you
