I can't speak to the lingerie dept. in particular, but I wanted to say I can 'relate' to some stores just not being as good as others.
I remember raving about Macy's to my Mom, and taking her to a local store - it was terrible for her finding plus sizes. Same thing when we met up in Las Vegas for a vacation (completely useless, that Macy's store in the so-called 'Fashion Show Mall') and yet, I've since taken her to other Macy's stores where the selection and service were top-notch.
Hate to say it, but I think this is just something with dept. stores in general? Don't laugh, but I have a running list of "Good Macy's and Bad Macy's" in my head.
I wonder if the same is true of Nordstrom?
I have a little tiny, rinky-dink looking Nordstrom Rack store near my house, and yet on a recent trip to Boulder CO, I noticed a new Rack store there that was HUGE - half way across the parking lot, three levels high and so on.
Meanwhile, I don't think this means Nordstrom as a whole is bad at bra fittings, but that perhaps they also have the so-called "Good Nordstrom and Bad Nordstrom" problem, just like I found with Macy's.
You might be better off at a specialty lingerie store?
Hang in there, I know it's no fun to try and force yourself to go and do this sort of thing (I'm always so awkward when it comes to bra fittings), and then to come away feeling frustrated like this is no good.
I hope you try again - maybe not Nordstrom, but perhaps a proper lingerie store next time.