Cookies are in many ways the most difficult of almost all recipes to master for a couple reasons. Firstly, put ten people in a room, ask them what their favorite style of cookie is and you may get 10 different answers.
Adding a little water can cause the gluten-mimicking ingredients to add more volume to your cookie, which will make them hold more air and expand better.
If your cookies spread too thin, add a little more flour.
If they don't spread enough, flatten them using a glass cup or coffee cup with a flat bottom. Spray or rub a little oil on the bottom, and press each dough ball down before placing in oven.