I can relate to this. It took me ages to come up with a complete projects list. I think the more you become aware of your project list and all the next actions you've committed yourself to, the more overwhelmed you can get with the depth and breadth of your committments, and realisation that you need to say no which you fear. I fear 'no' because I fear it will cause rejection, that people will think less of me.
But by taking on to much and doing it all badly, I risk getting that anyway.