If it wasn't "right", you wouldn't be seeing losses. Your body knows what the right level is for you and it sounds like you're clearly doing it. I swear losing weight can be frustrating sometimes because it's such a visible process and everyone is an "expert" on your body and what you should be doing. If it's working for you - don't change it!!
You may find after another 50lbs that you aren't losing as quickly as you'd like, then play with your calories again and see where you want to be. They are telling you what works for them but mistakenly applying that to you.
Congrats on your progress! Win that prize! Bring it home to 3FC!
