Baby won’t sleeep!!

Can someone pleaseee explain to me why my baby wakes up 3-4 times a night and will not go back to sleep right away!? It takes about an hour and half for her to fall asleep. I’m slowly losing my mind because once I’m awake I cannot fall back to sleep. I do a nighttime routine with her and I don’t let her nap too close to bedtime. I think this is worse than the newborn stage 😅