Oh OP my DD2 was like that. Between 12-4 she would wake for a couple of hours at that age. It probably lasted 2 months? Then she went back to waking 3-6 times a night.
I know it's not what you want to hear. But some kids are just bad sleepers. I tried everything bar sleep school. Nothing worked. We have just started having random sleep throughs at 2.5.
I changed naps, cut out certain foods, filling her up, cutting back food, warmer, colder... It made no difference. It did give me hope but that's all it did.
From a physical point of view I found the long wake ups the worst (excluding the hell that came before that when she would wake every hour and take 45mins to settle). I don't know, maybe I've just gotten used to getting up 5 times a night? Plus she's in a big girls bed now so I just lie next to her and drift in and out while she falls back asleep which usually only takes ten mins now.
One doctor suggested separation anxiety as the reason she's such a bad sleeper. Her grandparents are big parts of her life but come and go a lot. I don't know.
My mum told me that she's just a cr@p sleeper and would outgrow it at 2.5. It would appear she was right.