Rising problems

Hello folks!

I've been making this sandwich bread for a bit now:

https://www.kingarthurflour.com/recipes/classic-sandwich-bread-recipe

But shortly after I started making it, I decided it wasn't strong enough - it was falling apart sometimes with heavier sandwich fillings, so I switched to bread flour. Everything else the same. Now, the bread is still good, and is large enough to make sandwiches, but it doesn't rise as much as it should. it's maybe 1/2 to 2/3 the height it should be.

I'm wondering, should I increase the amount of yeast (and I think perhaps the sugar as well to feed the extra yeast)? Or or might something else be going on?

nb - All King Arthur Flour, so it's not substandard flour that's kicking me in the pants.