I have been in the marching band since
the 7th grade. I heard that this did not count as a sport though.
I realize band takes a lot of commitment, has physical elements and somewhat of a "team" environment. That said, it's not a sport. Thus, it counts, but not as a sport.
So should I join a spring sport this year and next? I cannot join in a fall sport because it interferes with band and I do not wish to quit something I have been doing for so long.
The short answer is "yes," you should join a spring sport. I suggest a team sport that requires running, such as lacrosse, soccer, spring football or a sport that requires a lot of strength and stamina, such as swimming, water polo, squash, tennis, etc. However, it's important that you do more than "join." You want to demonstrate a commitment and a certain level of talent/success, etc. Thus, my strong suggestion is to play this winter and spring and then do one or two sport camps this summer in the sport you've chosen -- if you can financially afford to do so.
Also I have not been in any clubs in school. Does this make a difference? Should I join something next year?
What do you do other than band? Are you involved in activities outside of school, such as church, scounting, etc.?
Also, it's not just about "joining" things -- clubs or teams. Rather than just join a club, figure out ways you can demonstrate leadership. Maybe it's within band -- are you in charge of anything for that or can you volunteer to take charge of some band project where you have to lead and manage people and things? Maybe set up a program where certain band members teach music appreciation to community children . . .
If not, what else interests you? What are your passions? For example, if you are an animal person, is there some way you can volunteer with a local rescue program and maybe set up a pet adoption program? If there is a particular subject you enjoy? You could start a tutoring and mentoring program.
As you can see, the possibilities are limitless. Generally, you are happier and more successful engaging in something that interests you -- figure out what it is and how you can use that to make a difference.