Clearly my kid is lazy because when I first saw the title I was thinking "7 is awfully large to be carried in a (baby carrier) bag."
Realistically though with my scouts we discourage drawstring bags because they are super uncomfortable to wear. Have you considered a LL Bean junior backpack (
https://www.llbean.com/llb/shop/118...ook-pack&bc=50-816&feat=816-GN1&csp=f&pos=8)? They aren't as cute as a
loungefly but they are super durable and work well for older kids too carrying a limited amount of stuff. That's what I made my daughter hike with until she complained that it was "too dirty." For Scouts. On a hike. Yep.
As others have said fannypacks aren't great for water bottles. We got one off
Amazon for a hike and I found that the bottles got in the way of my arms, and a single one (in the back) would not work well with rides. Plus it's a pain to have to clip/unclip it.