I would really have a talk with your boss about being overwhelmed with too many projects. I'd ask for clarification on what are the most pertinent projects and then explain briefly how in order to do good work on those, you need to have the other projects taken off your plate. Encourage your manager to use his delegation skills.

I have also been in work situations where the supervisors thought it was be a good idea to keep piling my plate on with more work. "But you do such a good job!" Yes, until I quit and then they got the message. Ugh.