My baby cousin

So my aunt had a baby April 1st 2017. My aunt asked me to be his godmother even though I’m 14. I love him to death he is my world. I post him on my snapchat all the time. He is my background on my phone ipad laptop and everyone at school says I’m too obsessed with him. I tell them I’m not but they say I am. A few weeks ago he fell down the stairs while my aunt was sleeping and had to get brain surgery while I was at school. I cried when I found out. I tell people he is my cousin and my godson but everyone makes fun of me saying he is my son and saying I’m too young to have a kid and it bothers me because I’m with him all the time because I babysit all the time. Am I too obsessed with him if I post him on my snapchat and he it’s all my backgrounds?