Is there any reason to think the boots that are size 12 won't fit my size 12 feet? I can size up to the 12.5 or down to 11-11.5's as well.
Sneaker size does not equal boot size. Also, one brand's size 12 is another's 11. Some brands make wider boots, others tend to be narrow. Salomon is usually a pretty narrow boot. They do offer wide versions if needed.
Long story short, it's really hard to find the right boot for you. So, going somewhere and trying on a bunch really helps narrow down what suites your feet.