i want to look normal

What can i do to look my age i am 19 years old ,but according to my 8 year old nieghbor i look 12 .you know how bad that makes me feel .Its not even the little kids its adults too everytime i go to a appointment for like the dentist they ask where's my mom cuz i cant be there if my moms not here.I am a grown ass women im just really short man and i feel like crap when they mistake my age.