How many calories should I be eating?

I apologize for this question because I can't tell you how many times I've seen it asked before, but I have been doing a lot of research and can't quite figure out how many calories I need to eat per day. I originally set my goal for about 1250 calories per day (I eat back most if not all of my exercise calories) but have recently found out that anyone under 21 (I'm currently 18) should be eating more than that. However, whenever I eat more than a net calorie of 1250, I always gain weight. Could that be my body telling me it's in starvation mode and trying to protect the body fat, or am I eating the correct number of calories? Today I increased my net calorie goal to 1400 but am really scared that I'm going to gain a lot of weight back. I've read in a few places that anyone under 21 should eat at least 1500 calories per day, but I don't know if that means a net of 1500 or if that is the number of calories I should eat regardless of how many calories I burn through exercise. I apologize if this is confusing (I'm kind of confusing myself also).I'd really appreciate any feedback and if you're confused I'd be happy to try to clarify! Thanks!

Edited to add: I'm 190 pounds currently and 5'9". I work out around 6 times a week and burn on average probably around 300-400 calories per day. Also, my TDEE is 2054 and BMR is 1712.