Hi, Rhythm,
Which athletic teams you choose are important. I totally agree that you need to choose something you will like doing and will want to continue. Swimming is a great choice.
When my daughter had a knee issue last Spring and couldn't run before R-day, her physical therapist pushed her to swim laps to build endurance and keep her muscles toned while she wasn't able to run. He said that runners that try to swim competitively don't do well, but swimmers that go into competitive running don't have a problem.
She loved the freedom of running, and she grumbled the whole time she was swimming that if she had wanted to swim she would have applied to the Naval Academy. lol
Cross-country is a great sport to find out how you feel about running, which you'll do a lot of at WP. If you don't mind being really physical, try flag football, soccer, or even wrestling. (Yes, schools have to allow girls on the school wrestling team, but talk to the coach first and get a feel for what his attitude would be.) If you aren't quite that adventurous, try softball, tennis, or golf. Also, try to do both a Fall sport and a Spring sport.
My d didn't start to compete in sports until she was a sophomore, so you do have time to get involved, but you need to start soon. Check out the Spring sports at your school now.
Good Luck!!!