Being a tomboy myself, and involved in many different sports even now, I had some of the same concerns when it came to my having a girl. I was a little worried that she would be too...girly. I was in denyal that she was a girl, until the day she was born and I was very apprehensive about her being too girly. I thought, what the heck am I going to do with a girl?
Rest assured, you will teach her what you know. In some aspects, girls are just that...girly. But,...they can be very interested in other things as well as long as you teach them who YOU are. My daughter loves bugs and worms, playing in the dirt...LOVES Frogs and catching them or playing ball with the neighborhood boys...and would prefer to play in the freezing cold outside...than to come in the house and play dolls. But, at the same time, she still loves baby dolls, pricesses, wishing wands and dresses. When you think about it more, and even ask your parents...you will probably remember being a little girly yourself. Playing with barbie dolls, wearing dresses non-stop at some stage of your life, etc. You just also learned that there are more to life than just dolls and make-up. You learned about sports and the outdoors and getting dirty. Don't you worry about her...she will be the person you teach her to be. A well rounded girl who will be able to appreciate all types of play...not just being a girly-girl. She is just like a boy, only better...because she can wear cute clothes too. Let's face it, girl clothes are much cuter than boys. Even moms with sons can attest to that.
Also,...think about when she is older and has her own babies...you will hopefully be able to enjoy all aspects of her life too. Not that you won't with a boy, but it's different with daughters...have you ever heard the saying, "A son is a son until he takes a wife. A daughter is a daughter for the rest of her life." Think about it...in most cases..it's kind of true. :) Don't worry...having a girl is wonderful! I'm a little worried I will end up having a boy someday...which I never would have thought when I was pregnant with my daughter.