I think it also depends on the size of the lemons you use. My zest from one lemon can be twice as much as yours! I used HUGE lemons, so mine were very lemon-y.
Also, I always tend to add an extra teaspoon or two of zest in all my baking recipes, because I always like more zest-y flavor than the recipes tend to call for. I think the measurements are approximations anyway - teaspoons are kind of arbitrary. Use taste as a guide Hehe, I usually have a teensy taste of the batter before I bake it (you know, in case I forget some major ingredient like sugar, which I did just last week!) and that's also when you can play with adding more zest.