I’m also hooked on cutaways. I would never buy a 12-fret reso without one, and I probably wouldn’t buy a 14 fretter without either. Unless it was really really pretty.
A National T-14 with an aftermarket pickup would probably make you very happy, but those are $5000+ new! I love mine dearly so sorry you can’t have it
The lower end of the market tends to stick more to “traditional” dimensions and features, which usually means 12 frets to the body.
Your technique is probably just fine! A lot of reso players disdain the higher frets, but I’ve always thought that was a waste. Few guitars can give you as much volume, sustain, and clarity above the 12th fret as a tricone played with a slide. And it’s a LOT easier to play up that high in tune if you’re not reaching diagonally across the fretboard with your slide.