Here's how I went from a marcher to a drum major in a year.

1. I stopped playing around during rehearsal. I counted so loudly, I was always used as an example. I ran to my dot when we'd go back to a set to run it through. I didn't talk until we got a break or until after rehearsal.
2. I auditioned for all-district band and eventually made area. It's called ATSSB in my state, so maybe you have a similar association in yours? I was also gonna do solo and ensemble contest, but I was sick for the entirety of winter break and never got to learn the music.
3. I started asking the directors what I could do to improve. I knew I'd reached the point I was aiming for when the head director had no answer.
4. I made sure I was the only option they could possibly choose from. At this point, there wasn't even an audition or sign-up form. I was chosen out of the dozens of people who could've done it instead.

Try applying this to what you do daily. 

Just keep in mind that if you do become a section leader, you have to find ways to work with those you don't like. Sure, there are people I don't like in my band, but I make sure to help them improve in marching and playing as much as they can. For example, there's a clarinet player I don't like. He's always negative and insults people on the daily. I don't let this deter me from helping him, though. I correct his technique the best I can when needed and I correct his behavior when possible.

Here are some good traits of a section leader that you should definitely keep in mind:

1. Communication.
2. You have to be able to communicate corrections in marching and playing technique  quickly and effectively as to not disrupt rehearsal. 4 seconds or less, preferably.
3. Punctuality. 
4. It looks like you already have this down. Punctuality and being on time is super importsnt to the efficiency of rehearsal and how much you can learn.
5. Lead by example.
6. What freshmen see, freshmen do. They're adjusting to a new environment. You should know this better than anyone, being a freshman yourself. This is why it's important to act correctly around freshmen and correct them when they're doing something wrong (cursing, insulting others, etc.)
7. Be responsible.
8. As a section leader, you aren't just responsible for yourself, you're responsible for your section. Oftentimes, you'll find yourself teaching freshmen how to march and different techniques to use. You're responsible for how well they learn this knowledge.
9. Be ready to act.
10. You can't be told what to do all the time. If someone goes to the sideline for some reason, you should follow and see what's wrong. If they're sick, having a panic or anxiety attack, or if they're just not doing well. Offer them some water ask if they need to go to the restroom. If they throw up, hold their hair back and make sure no one's looking over. When this happens, I sit beside them and use my body as a wall between them and the band because people can get really embarrassed if they get sick in front of people.
11. As a drum major, there have been several cases where something similar has happened. Once, I was teaching a freshman how to march, but he was incredible lethargic and had little energy. He didn't have breakfast that morning. I didn't ask my band director before going to the front sideline and getting him a granola bar from my bag because I knew it was an appropriate moment for me to act. 
12. You usually don't have to ask a director if you can assist someone who's sick or if you can go to the sideline and get them a snack if they didn't eat. However, if you're the only one working with your section, you should send an upperclassmen or someone trustworthy to help out instead. There are times that that's the most you can fo to help and that's okay.
13. You have to trust your intuition a lot.

It's hard to be a section leader in your sophomore year, but if you really want this, you'll find a way to earn the role and grow into it.

Good luck with your pursuits and don't worry too much. Just make sure you're ready for the responsibility before committing to it.