I have the exact same problem, I love learning new stuff, thinking about new projects, mentally designing code and UIs... but I do much less of actual coding done than I would want to. One reason is that once the novelty of the project wears of, it becomes a boring routine work.
maybe if you keep your projects in the "really small" size bin you can actually finish them before the boredom sets in. and the positive feedback loop might even prop you up to see a bit bigger projects through.
