The last is not the length.

Correct, but length is a key factor in size determination.

Width is a factor as well, and in one of the CS responses above, and based upon my size in their two other common lasts, they recommended a length of approximately 26.6 to 27 cm (as did I).

The width of the other two lasts were known, and fit me well, and the width of the 3rd last was compared to the other two by CS.

Instep - I think of the instep as the amount of meat on the top of my foot. I tend to not have a lot of meat on the top of my foot, and hence, I usually fill up the space with tongue pads.

Therefore, with me, average width, not a lot of meat on the instep, the primary consideration is the length.

In any case, just go stretch your shoe. Let us know how it goes.

I think I should probably do that.

Thanks!