Don't finish to finish—finish because a degree opens doors. That doesn't mean you have to get one. But a degree opens a lot of doors.

if something isn’t directly connected to serving and helping others, I’m planning my way out

It sounds like you want to work for an NGO. So figure out what major enables that. Accounting? Business management? I dunno, do some research. Email some NGO leaders. If you don't feel like you can take another 3–4 years, finish your polsci degree and minor in accounting or whatever.

motivating, coordinating, leading, challenging, and developing young people. What major is that?

Probably not one (maybe management?), but your Americorps experience should really help you there. You can get a degree in the most applicable thing, then use that plus your Americorps experience to get a leadership position.

I’m interested in everything

I didn’t have an area of interest

For what it's worth, I'm exactly the same. There are literally hundreds of things I'd love to do; and I didn't know what I wanted to do until I'd been doing it for about three years.

None of the interests you mention are STEM. So, I don't know if you have any interest or aptitude in STEM. But that's my area, so, I have a recommendation to consider, if you do: Operations Research.

OR is huge. It's a branch of mathematics, which directly applies to organising and making decisions. I'm convinced Apple exists today because Tim Cook is an OR genius. If you want to make a real, significant difference helping NGOs improve their efficiency and operations, and use their resources better, OR is a great choice. It's something a great many NGOs desperately need, and most don't even know it. It also opens more doors, like Industrial Engineering. If you have the maths aptitude, give it some thought.

I repeat: a degree opens doors. That doesn't mean you have to get one.

I always feel guilty talking about myself on hubski.

Don't.

Also, I'm in #denver. We all need to have a #meetup one of these days.