Proper leather shoes

yer thats what i kinda fear, but roomy is an overstatement. basically my heel can move up and down in the back by about 1cm. when i push my foot into the toebox theres just enough room for a shoehorn to slide in.

ive been trying them on and taking them off for the last 2 hours and still cant decide. I think 1/2 size smaller would be better but they sold out in the sale...

1cm is the difference between sizes. As yourself: would you be comfortable with over a 1cm of movement down the line?