Brannock sizing help

So I just realized I've been wearing the wrong size shoes this year (haven't bought any new shoes for 4 years until this summer). And I've been buying sneakers ranging from size 10.5 to 11.5(different brands).

I finally pulled the trigger and bought a pair of Iron Ranger last month at size 9 on a trip but it felt small after the break in, my longer second toe would touch the front after a couple hours of wear.

Since I live far from boot stores so I bought a brannock device and measured my feet. It indicates I'm a 12 by arch length and 10.5 by heel to toe. I posted it at the red wing sub but most people tell me I probably have misplaced the arch slider.

I have small knuckles so I tried my best to lined them up again and here's the latest result, still around 12, which would make me a 12A brannock. I'm wondering what should I do? Has anyone experienced this much difference between arch and heel to toe size?