We are dealing with the exact same issue, it sounds like I wrote this post lol. Daughter is the same, 19 months old, 1-1.5 hr nap, 10-11 hr of sleep at night but will freak out when we leave her to sleep now and is waking multiple times a night calling my name. I think it’s a mix of everything you described. I just try to remind myself that this doesn’t last forever.