I am 20 but I look like 14

Hello this is my first time posting on reddit, anyways the main part of that I am currently 20 years old 2006 born and i look like I am 14 years old not an ounce of facial hair my height is 5'5 weight is in the range of 50 kgs i feel horrible about this there isn't a day where I haven't thought about this that what mistakes must i have made that I look like this , no one takes me seriously every one looks at me as this cute little kid which I don't want to be , i am kind of going into depression just by thinking about this every day the worst is yet to come in a years time i will have to find a job and go to office with literal 40 years old while looking like a 8th grader i can't share my feelings with anyone because I have no one to do so