Am i underweight ?

Sorry to bother you all, im not sure if this is the right place to ask this but i didnt know where else to go, im 16, male, 5'8ft and weigh 99lbs, am i underweight ? Lately ive started to feel a little concious of my weight and appearance, my mums always said im quite skinny but ive never rly noticed how skinny until now, but idk maybe yall have more knowledge on this, and if i am underweight, any guides to gaining back said weight ? And apologies if this is worded poorly (Wait does this come under no medical advice rule ? Im not sure if this counts or not, ok i did get a warning before posting but idk where else to turn so if this gets deleted it gets deleted its wtv)