I’m gonna disagree a little about going shorter just because if you can get to the ability level (a little better than intermediate?) and fitness level (able to catch most session-worthy waves up to 1.5OH and larger dependably on a well-designed board of about 34-36L at 180 lbs), there are so many cool, fun design options out there in the 5’ 6" (and even smaller) up to 6’ 3" range out there for you.
I’m 215 lbs and surf “OK” at 46 – a little bit better than “intermediate” – surfing most every day (I surfed as a kid, didn’t surf for 20 years). When I first started making boards, I packed on the volume and the thick rails because (1) skinny little shapers in Santa Cruz rarely seem to understand how much volume big guys need and it was a pleasure to play around with huge amounts of foam in my same board lengths and (2) I can sink a thick rail at my weight. Since then, though, as my surfing’s gotten better, I’m gradually bringing the volume down, and going shorter and smaller, especially as my rocker designs and foils improve (causing the way my boards catch and enter waves to improve).
The trick is to get the balance of rail style and buoyancy, hull design, planshape and fin layout all working together. It sounds like for you your fish has something that was off about it for the waves you were in the day that the board disappointed you. My guess would be it was a combination of board-to-wave-mismatch, rail design issues, and rocker issues overall.
In my experience, at 180 you really don’t want that much thicker of a rail than a smaller guy (i.e. than the normal production range thickness). It sounds like there’s a good chance your (relatively noob) shaper has your rails wrong for your weight and ability/style at present.
Beginning shapers (I speak as one who is just now starting to make some decent rockers) rarely make good rails or good rockers, suited to the intended rider, unless they’re copying someone else’s design obsessively. I never made a board with a really good rocker til I copied a CI Whip. Only now after 16 boards do I feel like I kind of understand what rail shape/thickness to make for myself. I made a few boards with OK rockers before that, by sheer dumb luck, but never one as good as when I copied the CI. I made rails that worked in the past, but not as well as the rails I’m making as I get better at shaping and get a better feel for how to judge how water will or won’t bunch along the rail line when I run my hands up and down the rails.
All of that said, you can probably make that fish work if you just have enough fin options and find the right combination. Probably a larger fin that still allows you to go fast enough will help.
In terms of another rec for a small wave board, there are all kinds of Simmons hybrids out there, now. I have the most fun on my Simmons hybrids when waves are under waist high. That or longboarding.