I feel like I'm working very hard and doing my best in difficult classes, and I'm getting Bs

I mean, Bs are acceptable, I just got less of them last semester

and while I know that people get Bs and can still be premed/prevet/predental, I'm just worried that it's not good enough for grad school apps

why would they take me if they can take a kid who gets an A?

Depends on your major, but most people striving for a 4.0 is usually wanting to go to medical school, not particularly grad school.

And grad school acceptance isn't just your grades either.

By grad school I do mean vet school, which is pretty much the same as med school :/