Sleep advice 😩😴🧟‍♀️

Help moms! My almost 15 month old is still waking in the night. Now she stays awake sometimes for 3 or more hours 😩😩😩 we do the same routine every single night. Bath, pjs, milk, brush teeth, books, rock to sleep and then in her own crib. She sleeps with sound machine in a sleep sack. I know she can sleep through the night as she usually does about 1-2 times a week. But the rest of the time is a complete nightmare. I know we shouldn’t be rocking her to sleep. What should I do?! I’m exhausted 😴