I'd say she's behaving exactly as she should; other dogs are being rude and pushy, and she is saying to them "back off". Well within her rights. What is considered "normal, acceptable behavior" that people want their dogs to have (happy-go-lucky, leaping happy joyful at every dog they meet) is actually very rude and inappropriate behavior in the dog world.
What I would be doing (and am doing, as I have a dog who will also not tolerate rude encounters with most dogs), is to make a point to protect your dog a bit. She shouldn't *have* to feel like she needs to defend herself. You do that for her as much as possible. Obviously there are situations you can't prevent, but there are a lot you can. If you see a play date with even a good friend getting a bit to wound up, separate the dogs for a bit and let them settle. You already have stopped taking her to dog parks, which is where I see dogs being the rudest.
As for random encounters like the pug, I have no problem stepping between my dog and another dog who is going to bother her. If I'm "armed", I throw a handful of treats away from us to distract the dog while me make our getaway. If needed, a loud "GET" and a stomped foot will often back off the other dog. I'm sorry if I scare the other dog or upset the owner, but my responsibility is to my dog. I have seen an enormous decrease in her reactivity since I have started doing these things. She no longer worries about every dog we see, because she knows she isn't going to have to stand up for herself.
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