I really Ditto Riley J.
Each kid is also different.
My 1st child was a nightmare about sleeping and she was a bit colicky and sensory sensitive. But ate anything and everything.
My 2nd child was SO easy to put to sleep BUT he was a super picky eater since a baby. And still is, but he has NATURALLY, expanded his palate. He is now 4 years old.
I always go, by my kids cues.
Always.
We do not punish/reward about eating.
Both my kids, are super healthy and grow like weeds, and are tall lanky kids who have always been in the 97th+ percentiles.
My son is a grazer. Only eats until he is full. And LOVES milk. And drinks a lot of it.
My daughter eats heartily at each meal. Hates milk. THEN also has to graze throughout the day.... otherwise she gets really moody and irritable.
Both my kids, eat until they are full. Or they eat IF hungry. They know their body's cues for biological hunger or fulness. That is good. They do not eat to please me or out of emotional reasons or out of boredom. So, I have no problems with their food intake or palates.
I am also not a short order cook.
They eat.
Just differently than me or each other.
Its fine.
I know their cues.
They know it too.
We have never had food/eating "battles."
Next: NO, it is not a mandatory thing, that a baby at 18 months old is 'supposed to' sleep all night without waking.
18 months old is also a growth-spurt time.
My kids, woke and ate a ton, at growth-spurts.
For my kids, they did not sleep through the night, naturally, until about 2+ years old. Then it was a natural progression, that their sleep matured this way.
Just give your daughter, milk. She's not getting much.
They need the milk fats in it. Milk fats, is an essential nutrient... for brain development too. And it also helps, with sleep.
She is not getting much milk. Solids, does not replace milk intake.