Full Tilt is the first place I'd look. Note that they have 3 different shells on 3 different lasts (the foot form the boot is built around.) The Original shell (Classic, Drop Kick) is the narrowest, the Soul shell (First Chair, more recent Tom Wallisch) is a little wider and boxier, and the Evolution shell (Descendant, Ascendant, B&E, Kicker) is much wider with a really low cuff. With a narrow foot I'd steer clear of the Evolution shell, but the other two might work. Do a little Google search for basic fitting techniques, and go try some on.
In the FT assortment Drop Kicks will be really soft with a #6/90-flex tongue. For most people that's fine for park, urban, and riding with a very centered/upright stance, but they will fold over if you're really trying to drive into the boots elsewhere on the mountain. That said, flex is extremely subjective. Don't listen to the idiots that tell you you're not a real skier unless you're on a 130-flex boot. Personally it took me a decade of experimentation and evolving my riding style to find a few boots and flexes that matched. Luckily with FT you can just buy new tongues and swap them out if your stock tongues aren't working out (or if you just want to try something different.)
Outside of FT, but still in the 3-piece world, take a look at Dalbello Kryptons (or Lupos if you want a tech toe and a walk mode.) I find their fit to be a little more finicky and better suited to a high instep than FT's, but I'm currently riding some Lupos on Dalbello's narrowest last that I absolutely love.
FYI boots like Full Tilts, Dalbello Kryptons, etc. are 3-piece/cabrio boots (clog, cuff, tongue), and your standard 4-buckle boots from most other brands are 2-piece/overlap (clog, cuff.) There's some room for nuance in there, especially when you get into touring boots, but that's the gist of it. I didn't make any 2-piece/overlap boot recommendations because I don't ride them. I don't like they way they fit and haven't ridden one in probably 20 years.
Everyone gets that, but if you're seeing a bootfitter you're likely paying full retail for your boots. That just isn't feasible for a lot of people. Provided you do some research, ask the right questions, and know the basics of fitting a shell (again, Google is your friend) there's absolutely nothing wrong with getting an informed starting point from the NS crew.
**This post was edited on Apr 19th 2021 at 11:54:03am