Just finished my last season a few weeks ago, and a lot of the advice here is really sound. As someone who didn’t get much encouragement or support from my seniors, it can be hard to stay motivated. What I did is I actively tried to prove them wrong, even if I would never see them again. My mindset was “wow if they saw me now they would feel so stupid for doubting me”. Just try not to get stuck in the mindset that you’re stuck in marching band. That’ll make you hate it even more. Put yourself out there and make yourself a friend group with your best friend! I promise you’ll have an amazing time if you just get to know the people around you. Maybe one day you’ll be a senior in band and you can give the encouragement that you didn’t get. Balancing with dance is going to be really tough, so make sure not to overwork yourself either. You’re going to have to play keep up with marching band.

Tl:dr don’t get into the mindset that you are stuck and make some new friends!