I've been fitted in many, many different places. The only place I've found to be reliable in finding really comfortable bras are
https://www.rigbyandpeller.com
Completely worth taking a days holiday and travelling in to London, for me, from pretty much anywhere.
I first read about them in the '80's, an interview with the founder June Kenton who encouraged anyone contemplating. Breast reduction to try a fitting first.
In my early twenties, as a skinny 'very large breasted' self conscious wreck, I saved ferociously for ages, fully expecting to need a bespoke solution. Desperate to hide my shape, I was wearing a puffer style duvet coat when I showed up for my fitting.
As promised, not a tape measure in sight, the fitter gave me one bra to try on, saying it would help her gauge my size.
Stone the blessed crows, it fitted me perfectly.
Now, I return anytime I have lost or gained weight, so that I need a refit, otherwise order online. Not cheap, but really really brilliant value.