exercise and BMR

I have been throwing around ideas of how to set up MFP and I am so confused. I have it set up now that it is my elite nutrition guide number (I am doing insanity and it calculates your BMR, activity level, and what you should eat to lose weight on the program). My BMR is 1411 and with my activity level and cut for weight loss it leaves me with 1898 calories a day. I also have been adding in weight training, extra walks/ runs (I love to be outside), and yoga so I am burning more than just the insanity calories. Am I eating the right amount? If I add my exercise calories to my BMR and eat most of those back I will eat way more than 1898 value. I don't want to eat to much or too little as I know that those won't help me lose weight, so I'm trying to get the correct value of calories in to lose weight in a healthy way (I want to lose about 20 lbs yet).