Figuring out your calories is definitely like a science experiment and there are so many articles and calculators out there with varying answers.
I think you're not eating enough, if you are exercising that much! Try adding 200-400 calories each day and see if you lose anything. Also make sure your calories are coming from good foods, you know, whole grains, lean meats, veggies, non processed natural low fat foods. I definitely notice the difference when I eat 1800 calories of processed food versus 1800 calories of healthy food, not only in my fitness goals but my energy & stress levels.