Upload & Sell: On
Ok well that doesn't make it much easier...
Speaking for myself, if had your kit I'd only feel held back by lack of a fast prime and an off camera flash. Those would be my first two additional purchases. If you want to play with some more reach a 55-200 will amuse you for cheap, and, bought used, should be free when you sell it later for the same $. Macro is a lot of fun and autofocus really isn't necessary for it, so maybe an older macro lens (but not so old that it won't meter on your camera) for cheap.
Then I'd want to learn all the basics cold, and spend a lot of time shooting. Try to wear out that 3100, and get to the point where you're having fun making better pictures than folks with more $ than skill, the ones producing snapshots with $5000+ rigs. Wait, that could be me haha.