I can understand how upsetting this is for you but try to understand things from your mom's point of view, Things have changed a lot since she was your age and she loves you and therefore worries about things that could happen to you. Although you have known your friend for a long time,the fact that she doesn't know her parents is a worry. In her mind they might not be suitable (i.e drugs, perverts etc) I know it's unlikely but it happens and you are her world. That said, she is being over protective and that needs to be addressed. When my daughter was younger a friend came to stay overnight and her parents had not met us, so her mom popped in for a while to introduce herself and make sure we are people worthy of her daughter. As a parent I totally understood that, and so will your friend's mom. Why don't you suggest to your mom that she meets your friend's parents? Not only will it put her mind at rest, if they become friends she might be able to convince your mom to give you more freedom. Good luck, I know how it feels but believe me, it is done out of love.
My mum won't let me go anywhere! I asked her if I could sleep over my friends house and she said she didn't know the parents well enough to let me! I’ve been friends with her for a year! she doesn't let me go on my own for longer than 1 hour. Why?
Talk to her about how her controlling behaviour is making you feel isolated, I feel so sorry for you! :(