Replying to Boot sizing question

for the life of me i cant figure out how to fit my boots. i got fitted a few years back and packed into a 27.5, but even after that packed out, my foot was cramped (and i got major shinbag, probably due to the shittiness of the boot). i wear a size 10 shoe, that actually fits me, in fact, my toes touch the end of my shoe, kinda strange, but im used to it. i wanna go with a 28.0 foil, but they feel just SLIGHTLY large for me, it could be that im used to cramming my foot into a race boot from back in the day, but im also flat footed, which probably doesnt help things. any ideas?