If this is the first time you've really ridden a bike as an adult/ridden a road bike -- I would suggest giving it a good month or two before thinking about the stem at all. You will adjust to the position and probably stretch out a little (or possibly realize that you're already too stretched out, but you probably need to put some more time in to tell the difference, as others have pointed out, between bike issues and new rider issues).

As for handlebars -- I think most women (though someone will certainly contradict me here, so definitely not all women) need smaller handlebars than are spec'd on the bike. You might go into your bike shop and have them measure your shoulders, and get their opinion. You could probably also go in and "hold" different sizes of handlebar. It's not on your bike, but it gives you some idea. (Not all bike shops stock bars in sizes smaller than 40 though).

My bike came stock with 42cm (c-c) handlebars -- this always felt awkward to me and I had some hand pain issues. I switched to a 38cm bar (my shoulders measure 38cm), and it's drastically more natural feeling and comfortable. Though now, having ridden with the new bar for a few months, I occaisionally wonder if I might want a slightly bigger bar (but still smaller than the original) for greater leverage... my point is that some aspects of fit can be a work in progress, since as you ride more and more your riding style will change and you will want different things from your bike.

Hope this isn't too rambling to be helpful . Good luck!