Healthy weight vs ideal weight

ash

Hello lovelies! My backstory is I went from 148.8 to now 120.6 this year with help from a doctor. He put me on 800-1000 calories a day and now has me at 1590 for maintenance, but I’m still losing weight which is getting me closer to his “ideal” weight for me, but I don’t think it’s a healthy weight.

Anyways, how do you all calculate your daily calories, ideal weights, etc?