I totally understand that :-)
Be sure to plan always something that is achievable within a certain time-frame. I think the trick is to get good at guessing the scope of the idea for a game to fit into that time-frame and be achievable with ones current skill level.
You can do it! ;-)
GMTK Deadline Missers Jam » Entries » Macaron Simulator, an Out-of-Control sandbox RTS (Yellow Jackets parody for GMTK)