The famous Toll House cookie recipe is very similar to yours, and they always come out either flat and chewy, or flat and crispy, depending on the cooking time. This is because they are leavend with simple baking soda, with no acid to create the CO2 required for leavening. Replace the baking soda with baking powder, and add a tbs. of water to youre recipe. The water will work with the flour starches, creating the proper texture to trap teh CO2 and expand the cookie. This will give your a tender, more cake-like cookie. If you simply want a thicker cookie, but with the same chewy texture as the Toll House cookie, increase the amount of flour with respect to the amount of fat. Add and extra 1/4 cup in your recipe.
If you add unsweetened cocoa powder (make sure it's not ductched), then you can use the baking soda as the cocoa powder is acidic enough to react with the baking soda. And, you will have a chocolate cookie with chocolate chips.
Just some suggestions. Hope they help.
Seeeeeya; Goodweed of the North
“No amount of success outside the home can compensate for failure within the home…
Check out my blog for the friendliest cooking instruction on the net. Go ahead. You know you want to.