Help! i think i have melanoma!?

hi im 14 years old and i was born with this birth bark on the side of my thigh. One time when i went to get a check up my mom asked the Doctor to look at it. she said to go to a dermatologist but she look very concerned. It hasn't changed in shape but its gotten bigger...i think its because ive gotten taller and my skin stretched. I noticed that my mom has a birth mark on her cheek that looks exactly the same as mine but it is very small...i looked at a picture of her when she was my age and she didn't have it. please help im very scared and i hate doctors i pray every day to God to please tell me what wrong with me. im scared that im gonna die.... please help