Is there a protocol for this?

Okay, so my dissertation supervisor has had my introductory chapter for about two months now. She indicated when I passed it off to her it would be a few weeks.

Ordinarily, I would not consider this a problem. But I've just finished drafting chapter 1 and I'm not sure what I should do. Should I wait to get the introduction back before sending the first chapter? Should I send it off anyway? Am I being annoying if she has two chapters at one time? Should I email (again)? (I emailed a week ago to say chapter 1 was in the final stages and to ask this very question - no response yet)

I can continue to work, but frankly, chapter 2 is also on the doorstep - that is, it needs one additional small section added and some serious trimming of the rest, but most of the content is there. If I don't send off chapter 1 soon, there's a very real possibility that chapter 2 will be sitting around as well, waiting to be sent off!

So, any ideas out there what the protocol for this kind of thing is?