Losing weight while growing?

Ok guys. I’m here to ask for help. Not to brag about anything. I’m making that clear. Ok, let’s begin.

When I was in 4th grade, I was gaining weight. The doctor told me I was totally fine. I was “normal”

A couple years later, I started to grow taller and thin out a bit. I never starved myself or tried to lose weight.

A couple months ago (I’m 13) And i was 5’4, 109 pounds. Keep in mind some BMI charts said underweight and some said normal.

I decided I weigh myself since that’s a good thing to do. I was shocked to see the results.

Turns out I am currently 106 lbs. height did not change. I should be growing. I recently talked to my mom about it, and she said, “are you trying to lose weight? You’re probably sick. You have something wrong with you.”

It made me feel terrible. I would never do that. I would tell my mom if I was anorexic.

I need your guys opinion on what to do.

1) go to a doctor

2) don’t worry about it

3) start eating more

4) other (comment)

Please comment a number or a suggestion. Thanks for reading and have a great day! :)