Confused about bmr/calories

I'm hoping to understand how many calories I should be eating. Every calculator online seems to give a different amount.

I'm 150 lbs. Down from 159 since thanksgiving. I'm hoping to lose 20 pounds. I have been working out usually 4 days per week. I'm using insanity and mossa fight workouts right now but I have an Xbox one so I have access to other programs and a gym membership and sometimes switch it up. I give it my all and am really covered in sweat by the end.

I'm not sure if I'm eating the right amount though. I have tried the 1,200 calories but I felt hungry. I've been eating 1,400 and feel better. I calculated my bmr and it was 1,500. So I'm confused. Am I supposed to eat that amount? Should I eat more, less?

This site says I should be eating 1,760. That seems like a lot to me. I have lost 9 pounds in about 2 months so 1,400 is working as far as weight loss goes but I don't want to eat too little and end up gaining it all back.