Baby Won’t Sleep

My 5 week old spends way too much time awake some days. She sleeps about 14- 18 hours every other day but the other days she sleeps around 8 hours if that. She definitely is getting enough to eat (nursing + bottles + 8-10 wet diapers), we have the same environment for her to sleep in everyday, she’s not fussy at all when she’s awake, just WIDE AWAKE. She will fall asleep for 8-15 minutes at a time and then be ready to go again for another 2 hours. Today it’s 3pm and her longest sleep since 4am has been 20 minutes. In total she has slept only 4:51 today and she’s currently just chillin happily in her swaddle kicking her legs around. Any pointers for why she might be unable to sleep? (I drink the same amount of caffeine every day btw).