Hi hun.
I'm not Barb, but I just wanted to let you know my experience. I was always under the impression that bubs needed both sides at every feed, so when DS was only feeding from one side I was a bit confused. I did try the second side, but it never was taken. Then I had a lady at the chemist say that because he was feeding 2 hourly, he needed that second side. I listened & decided to feed him on the first, then detatch & feed him from the second.
Big mistake. Within a few days I was severely engorged & had lumps under my breasts that felt like massive bruises. Blocked ducts. So I ditched the advice & went back to one side at a feed. Everything fixed itself & I was very relieved!!
I fed til he either slept, or detatched himself, then I would sometimes do a nappy change & try the second in case he was still hungry, but he rarely took it. I eventually didn't worry about offering as it was never taken & if he wanted it he'd let me know.
So, after all that! I'd say follow your babies lead If she seems happy with just one side, then I'd leave it at that. Your milk will produce to how the baby feeds If you feed & she falls alseep, but wakes in a few minutes, she might be wanting the second side.