Don't worry Amber I think everyone has their own issues with song writing. Mine is that I once I get started on one song I end up starting about several different partial songs all at once and then failing to bring the first one (and it's babies) into any kind of order. Mary M will testify to this as she has seen my dodgy werewolf offshoot song!
So banging on comes naturally to me, whereas brevity, planning, completing things and finishing a song doesn't.
Like Mary says, the journal thing's a good idea, if it's 'train of thought' it doesn't matter because as long as you can roughly 'chunk' it up into themes, you can team up with someone on here who will help you structure it and tease it out with you into a song. So technically you've started on the path to getting a song done by appearing on here.