Postpartum insomnia

I have a five and a half month old. It’s our first. I don’t know what happened to me but I can’t sleep anymore. I used to be able to go to sleep and sleep8 plus hours straight. My daughter has never slept through the night but lately she’s doing better she’s sleeping four plus hours at a time. In fact last night was one of her best and one of my worst. I went to sleep at 8:30 and couldn’t fall asleep til 11. I was just laying there. I never had insomnia before having a a baby. I started taking melatonin to help but it’s not doing much. It seems it comes and goes- one night I’ll be able to sleep ok and fall asleep easily and then I have nights like last night. I’m supposed to be staying in a hotel In a few weeks to give myself a break but I don’t even know what the point is. I think I’ll be up all night anyway. My body is now programmed it seems to not sleep long anymore. And the not being able to fall asleep is just awful. Can anyone tell me if they’ve had tbjs before and what did you do? I asked my ob for sleeping meds but they don’t want to give it which makes sense bc there addicting And I don’t want to not hear the baby. I hope things get better. I miss sleep. 😩