Sip all night too. I couldn't seem to get rehydrated until I started keeping Water by my bed. I keep a 24 oz bottle by my bed. (3oz x 8hrs).
Just remember that you don't eat and drink at the same time. It's not an important distinction today, but it's coming soon. Try to think of nutritious liquids as food. Then Water is for thirst. That might help with the feeling you are "sipping all day". (My surgery was almost 3 weeks ago.)