Im tired of being called skinny, really tired. help? :(?

I weigh 99-101 IBS and im 21 years old, whoever i face they say "ur soo skinny" ... or "ur getting skinner everytime i see u " or .. "do u eat" ....or "u should eat , ur not eating and becoming this" ... "u llook like a pencil" . Im tall and skinny and chicken legs and i hate how ppl are telling me **** about how skinny i am, i try to not care and love who i am but its just bothering the heck out of me, i see myself in the mirror and say "im not THAT skinny as ppl say, im just normal"" but i dont know how ppl see me?! :( I have tried squats and lunges and got shakes from the GNC store for mass muscle build up, but nothing seems to work and i dont gain muscle or fat or anything at all!!!!!! I really want to gain but i have tried that for 1-2 years now and nothing has changed but gettign skinnier everyday, even old ppl who i have seen after couple years/ strangers all have that one sentence for me " why are u getting so skinny? " :((( what should i do? ive seen worse than myself, but i just feel everythings coming towards me :(