Split night hell… again

So my daughter used to get split nights ALL the time. I tried everything, less day sleep, later bedtime and nothing really worked but eventually it stopped. She is 15 months and recently transitioned to one nap as she was fighting the second nap hard and also fighting bedtime as well. we are now back to split night hell. Is this normal when going from tw/o naps to one? I don’t think I can take her doing this for months again it’s so difficult. She’ll be awake for 2 hours at like 2/3am! she usually gets up about 7 then we’ve been doing first nap at about 11:30 for 2-2 1/2 hours then bedtime I usually can’t get her down before about 8. Please help😩