Disney is so great about accommodating people, so I would just call dining reservations and ask if that is something they could do. Maybe they can just make a reservation for 8 for you (i.e., a whole table) and note that there are fewer coming but that you had a special need for your own table. If they can, they'll make a note on the reservation. As others have mentioned, lunch is often quite a bit less crowded than dinner, so may be easier to do then.
Those people on the bus are terrible. But just remember, some people are just jerks, but not everyone is. I remember one time we were stuck on the tarmac at MCO waiting to take off on our evening flight home for 5 hours due to a mechanical issue, and my 5 year old just couldn't take it any more. I tried to put on a movie or ipad app with headphones for him, read him a book, give him toys, but he was just tired and cranky and couldn't help whining and crying, no matter how much I tried to comfort him or distract him or gently remind him about indoor voices. A bunch of people around us were complaining about brats and bad parents who shouldn't be allowed to fly, and one even called the stewardess over to demand that she "do something" (not sure what he had in mind, but the stewardess must be a mom herself, because she immediately told him he is a small child and can't help it). My nerves were frayed to a thread by the time we got home, but then an elderly gentleman stood up as soon as the seatbelt sign went off, walked quickly up to us, and loudly said for the other guests that he saw everything I tried to do for my boy and that I am a wonderful mother. It made me feel so much better, and I always try to pay it forward when I see another parent in a similar situation, so just to confirm: You did nothing wrong on the bus. You are a wonderful mother.