love/hate relationship?

I haven't been posting too much lately because I dont' have a lot to say. Mostly I'm stressed out with too much too and not enough time. My advisor started talking about starting another project the other day and I about lost it! I'm already working on about 4 different projects, taking class, TAing which is adding a lot of grading, and training 3 new people! I have no time to research, build and try a 'new' project that has not been attempted before. We have been trying to get our electrophys project off the ground for a while now and that has been frustrating, frustrating, frustrating- I can't start another ambiguous project, pumping loads of time into it and not have it pay off. Argh. I told her I would not work on it and she said ok so I guess that is fine for now.... but I know in a couple of months it will be there waiting. If she gets this started and off the ground swell. I just end up feeling guilty because I feel like I should be helping out by developing a new task. That is a good opportunity and I don't want to let my PI down, but right now I have too much on my plate. Picking a lab is sort of like dating, you pick a lab because of certain qualities that attract you. For me it was that the lab had a lot going on and was diversified so that I did not have to pick one type of task and devote my life to running it over and over and over with just small differences. But over time setting up new projects takes so much time and figuring out the bugs takes even longer. Picking just one behavioral task means you save a lot of time. I guess it is a trade off. Anyway, I learned in a relationship class that the same traits that attract you to someone, can later become twisted so that in a 'cognitive negative framework' the same spontaneity that drove you to a person starts to drive you crazy because they have no schedule or real timeframe. (or something like that). IE. My lab's once attractive diversity is now starting to unravel the lab... or me? Maybe if I find my motivation I can work through this and learn to love my lab again, it's a work in progress.