figuring out fit

[VeloVT]

Regarding keeping neutral wrists -- have you looked at how well the handlebar width suits you? I recently switched out my handlbars from the 42s that came on my bike to 38s, and it made a big difference -- wrists are better positioned, shoulders/arms feel more natural, and I feel more in control of the bike. Also you might look at different drop shapes (traditional vs a wide variety of ergo shapes), this could affect your wrist position as well.

I wasn't able to understand from your post exactly what problem you are having with breathing -- it sounds like in most positions, you can breathe OK but your saddle is uncomfortable. Can you describe this issue more specifically? Is there a position that actually makes it difficult to breathe?

Good luck with all of this!!!

Edit: Sorry, I didn't read that you are riding a mountain bike. Guess my handlebar suggestions are not all that helpful then -- though you might still look at size, or -- I don't know anything about mountain bikes -- but maybe more of a "riser" bar would shift you into a more comfortable position? Could your reach be too long?