You are correct. A 100% het is a gene carrier, but looks normal. If you breed a het to het, each egg has a 1/4 chance of being a visual, 1/2 chance of being a het, and 1/4 chance of being a normal. Therefore, the normal looking off spring are 66% possible hets, which means they may be hets or normals. You do not know without breeding them.

Hope this helps.