Is it okay if I ate less than 1200 calories today? Will my body go into "starvation mode"?

I really can't eat anymore, plus it's already late. I ate less than 1200 but I'm pretty sure it's more than 900. I woke up late and I just don't feel hungry at all (I used to eat soo much). I'm 17, 120 pounds and 5 ft 2. The thing about my body is that every pound counts and I actually don't wanna lose any weight because my BMI is healthy and I'm at quite a good weight for my age and height but I'm flabby and I've got a lot of fat (my body is actually naturally small but I've never been "thin" because I've always eaten too much). I've always been a bit chubby. I don't wanna be stick thin, I just wanna get rid of most of my obvious fats. I used to eat about 800-900 calories and would lose weight so rapidly then gain it all back so I don't want it to happen again :(