Re: when just feeding on one side?
How's her weight gain going? IIRC your first few posts were about some concerns you had over your baby's weight...?
In general, if baby is gaining weight adequately, feeding on demand, and producing the right number of wet and poopy diapers, you can safely allow her to nurse on just one side per feeding if that's what she seems to want to do. If your supply does drop, your baby will be able to boost it right back up by nursing more frequently, taking both sides at a feeding, and emptying the breast or breasts more thoroughly when she nurses.
Coolest thing my big girl said recently: "How can you tell the world is moving when you are standing on it?"
Coolest thing my little girl sang recently: "I love dat one-two pupples!"