Like Sarita said that’s up to you and how you think your bunny is doing. When I just had one bunny he basically slept all day when I was gone. I think now that I have two, the also sleep all day, but I imagine they get up every once a while and doing some bunny communication or something and it’s probably not as lonely.
However, if you were going to get another bunny, because you’ll be going to college again soon and won’t have so much time to spend, I would recommend adopting an older, already altered bunny. Getting a younger bunny will mean waiting until they are already altered before you can begin the bonding process. If you can find a bunny shelter, they usually actually let you take your bunny in for bonding dates so you can find a bunny that your current bunny may have an easier time bonding with.
As for litter boxes, it depends on how much space you bunnies have. My 2 bunnies have 3 litter boxes but they’re pen is about 10×5′. Bonding can also be pretty time consuming so there is that to also think about. But if you do decide to get another bunny, I think they seem happier having each other now. They don’t require so much attention from me either, they entertain each other.