Thanks guys, I actually had no idea I'd have to re-check my bag - I assumed it'd just head off to Boston and I'd see it there! A little internet research educated me as to why that is.
I called United today as I'm visually impaired and had to inform them I'm travelling solo. I'm a little nervous about finding my way around, I can see well enough that I don't need help but it takes a while to figure out where I'm going in new places. I'm sure it'll be fine though.