so i want to be a fashion designer but i just don't know....

ever since i was small i used to make my dolls clothes ofcourse it wasn't perfect and everything but that's what i liked to do.But everybody just laughs when i say that i want to be a fashion designer exept my grandmother.so i don't know what to do i just love fashion and know that i got the sewing machine for my birthday i want to create more and more but my dad says that i rather be a doctor than a fashion designer.He says that you have to help people but i hate doctors.I am just a 13 year old girl i know i'm just too young to think about work yet but should i trust my feelings and keep doing what i am doing i just don't know.fashion is my pashion i love it!so please help!