You seem to recognize that your weight loss, counting calories and not having regular periods may all be signs of a health concern such as an eating disorder. It’s great that you are being proactive about your health and wanting to prevent health problems!
If you are not taking in enough calories from the food you eat, this can cause irregular or absent periods, as well as low blood pressure, hair thinning, dry skin, fatigue, and many more symptoms. The first step is to make an appointment with your health care provider (HCP) and find out the cause of your weight loss and lack of periods as well as why you are focused on counting calories. There are many other possible causes of missed periods including pregnancy (if you are sexually active), or a medical condition such as a problem with your thyroid. Talk to your HCP about meeting with a dietitian who can help you plan healthy meals and snacks so you can get the calories your body needs to be healthy.