Too skinny

I am a sophomore in high school but I’m seriously underweight. I weigh 95 pounds and my height is 5 1/2. With how skinny I am, it’s caused me to have bad anxiety about how I look. I go to school and of course I have physical education class, I don’t know what I’d have to wear for that class as we don’t have to wear uniforms but I wanna wear shorts. I’m not sure what other pants I’d wear other than leggings but the dress code is it can’t show underwear and I don’t know if my leggings are see through. What pants or shorts would I wear for the class? I just feel too scrawny to wear anything and I need help. (Sorry i babbled on about a lot in this, I really don’t know how to explain what I’m trying to say, I’m bad at explaining things but please help.)