drink sizes
Hey Kim,
You aren't going crazy, it is true that a traditional cappucino is quite small - this is why they are rarely popular in the US. In Italy and other countries they are often served in small, 4-5 oz ceramic cups. Yes, a shot of espresso is between .75 and 1.5 oz. And yes, a cappucino will not fill any of the typical cups used in the US and possibly also Canada. I would ask unfamiliar customers if they would like a wet or dry capp, to ascertain what they really expect in a drink. Some will no doubt give you a quizzical look, but if they do not know what you mean they probably want something closer to a latte than a cappucino. Many shops make this "lattecino" more often than not, with few complaints. (Unless the epresso blend is itself quite mild, in which case it could get lost in too much milk.) In a 12 oz latte, I recommend 2 shots espresso, then foamed milk to almost fill the cup, with a dollop of microfoam on top. This may be a little more milk than classical definition, but is popular in many markets. You would add another shot for each increase in size; 16 oz lattes would get 3 shots, 20 oz get 4. Some people just don't quite fill the cups, others give more foam on top to fill the space. See what your customers have to say. They will offer opinions if you ask for them. (also sometimes when you don't.)

Don't forget that flavor syrups take room too; they are popular here and can be present as much as 2 oz in a large size.
If you are uncomfortable serving cappucinos in half empty cups, try a small size just for them, as long as space permits their storage.
good luck and feel free to pm me!
Kim
Crave Espresso Bar, Tucson AZ