How can I get my 2 year old to sleep through the night?

My two year old wakes up every 2-3 hours almost every night, and I cannot figure out how to break her of this. It has been going on for several months now.

We changed her crib to a toddler bed shortly after a year and she slept ok for a while. But then she started to be up every few hours and we assumed her baby mattress wasn’t comfortable for her anymore. So we moved her into a nice comfy twin sized bed. The first week she did great and only woke up once or twice a night. Now she’s up every 2-3 hours like a newborn and it is driving me insane. She comes to get me and asks me to rock or sit with her. If I try to just lay her back down and sit beside her, she screams and screams. And sometimes I let her until she wears herself out. I’ve told my husband she is way to old to be doing this and it has to stop, but I don’t know what to do. I’ve even tried the zarbees melatonin gummies or juice (approved by my pediatrician) and those don’t make a difference.

I don’t know what else to do. If she woke up once or twice on occasion that’s fine but she really is almost every 2 hours regularly, every single night.