Change in Nursing Habits?

Hey mamas, I'm sure this is normal cuz babies are unpredictable, but just wanted to make sure! My little one is 12 weeks today, and up until about a week ago, she was nursing for 15-20 minutes per session, and would nurse right after waking up. We had a pretty regular pattern of eat-play-sleep. Now in the last week or so, she'll nurse for a few minutes, then get pissed off until I sit her up or play with her. Then she'll cry a while later and want to nurse for another few minutes. She might be satiated in that second feeding, but sometimes she wants to eat again before going to sleep. This is stretching her awake time to 1.5-3 hours, which is abnormal for her. Usually she's awake for 1.25-1.5 hours at a time. It's definitely not a supply issue, as I overproduce and donate milk. Is it just that she can see more and gets distracted? Just a phase? Anything I can do to make her eat her fill all at once? It's making it hard to do anything!