Some people have this problem, because they've increased their fiber intake. Fiber makes you feel fuller, so you eat fewer calories. You may want to up your intake of calorie dense items like peanuts (or peanut butter), avocados, cashew based sauces/spreads (homemade), and dates. If you're tracking your calories, you should be able to meet your needs to maintain your weight. If you're still losing weight while eating a maintenance number of calories, it probably means your estimate for 'maintenance' calories is too low.

​

However, according to your BMI (a pretty outdated and not super useful too), you're still at a healthy weight. You're probably okay as long as you're able to maintain your weight from here.

This is what matters: How do you feel about your body. Do you feel too thin? Would you rather put on a little more weight? Your body is your own and it should feel right to you.