Making sugar cookies from scratch. Gluten free. without a recipe.

I should say, recipe for disaster.

Let me preface this post with "I am not Suzy Homemaker"- I'm not even her distant cousin. I love to bake, and I am usually decent at it, when I am marginally following a recipe.

Today, I decided to throw all caution into the wind and replicate the sugar cookies from a box that we had a few weeks ago. The cookies were goooood... but they were $6 a box for about a dozen and a half cookies, so I just couldn't bring myself to buy another box. I tried to remember the appropriate ratio of wet-to-dry ingredients, and may have sneaked a peak at the back of the box last time I was at Econo Foods.

So I started with a stick of Jilbert's butter (that's half a cup), a quarter-cup of Jilbert's skim milk, and two eggs. Beat this with my Kitchenaid and streamed in ~1c cane sugar. I then mixed the dry ingredients in a bowl- 1/2c Bob's brown rice flour, 1/2c tapioca flour, and 1/2c cornstarch, with ~1tbsp potato starch. I flaked off the insides of one vanilla bean, and added another 3/4c or so of cane sugar to the mix. Mixed the dry into the wet ingredients, and the soupy-mix was scooped into spoonfuls onto a greased baking sheet. Baked at 375F.

Try #1- Cookie Smudged.
The cookies completely converged. The cookie sheet was just a smear of cookie mess. Tasted good though.

Try #2- added about a 1/2c rice flour to the mix. Re-scooped on the cookie sheet. The cookies still smeared a lot, but looked ok... until I tried to take them off the cookie sheet. That's the way the cookies crumbled.

Try #3- Chillin' the dough. I threw the dough in the fridge for a good half hour. Didn't change a damn thing.

So, anyone got any ideas? What did I do wrong?!
It's worth noting that I love cookie dough and cookie crumbs, so it wasn't a total waste!