Congratulations on your lovely baby!
Have you spoken to a medical professional about this? I mean, a midwife, a breastfeeding counsellor or lactation consultant? It sounds unusual to me, tbh, at that age mine would be feeding for aaaaages.
Is she very sleepy? Has she any other unusual symptoms? I really would recommend talking to someone IRL as soon as you can. I don't want to alarm you. The only other time I have heard of similar behaviour, baby simply didn't have the energy to feed as she had a heart problem. It was fixable, as it was caught in time, but it was quite serious. Again, I don't want to alarm you but I would get her checked.
Her problem caused poor circulation, another symptom was purple feet.