Sleep Changes

Hi mamas! Just wondering - have your little ones sleep patterns changed? Mine is almost 14 weeks old. At 8 weeks, she started sleeping for 8-9 hours at a time. By 10 weeks or so, it was 10-11 hours. It was fabulous! But now she's consistently waking around 1am/2am, nursing, and then waking up again anywhere between 4 and 6 to nurse again. She then might go back to sleep, or if it's closer to 6, she'll have her usual awake time of 1.5-2 hours. I was waking to pump around 1 or 2am anyway, so it's not that much of an annoyance to me, I'm just curious about why she changed! Any thoughts? It's been going on for about 2 weeks, so I don't think it's a leap, probably? Also, she's pretty big - 99th percentile in height and 85th in weight - so I would've thought that would mean she'd sleep longer!