Weight loss EBF

Please no rude comments. I quickly lost all my pregnancy weight thanks to BF. Now I'm down an extra 10lbs (completely not needed...I am a very naturally thin person to begin with). Is it normal to have a hard time keeping weight on when EBF? And yes....I eat 3 meals per day, snacks, etc. I've started adding extra stuff to my meals just too add healthy fats (like peanut butter to oatmeal). I know you need to eat more, which i am...I just keep dropping weight! Normal??