You have obviously given the bike purchase alot of thought and research. The bike you got is much nicer, components wise than the Trek. Did you spend as much time riding the Trek as the new bike? Every bike is different, and you just might need a little tweeking. Give yourself some credit and don't second guess your decision. Tell the bike shop your concerns and give them a chance to take it back. If they refuse then work them for the best fit you can get. I think a shorter stem will still give you the handling you need. Saddle position and the pedals will help you get where you need to be. If you absolutely hate it, take pictures of it and have it professionally boxed up. Put it on road bike review classifieds for two bucks, and ebay. Someone will buy it and go get something else. I've gone through two and it's always a work in progress. Good luck.