I can kinda understand what you are saying, I too was in such a similar situation. I know its not ideal but I went to the doctors, went to counselling and took medication without my Mum knowing and when I felt stronger I told her. I told her I didn't need her help cos I could do it on my own but I did need her support and understanding - ok so it wasn't a rosy ending and she didn't really say a lot to me about it and still doesn't talk about it much but at least I feel better about myself.
If you talk to your GP you know they can't tell your parents unless they think you are going to harm yourself or someone else. I urge you to bite the bullet and go for it.
Keep posting on here too cos it helps to just get things off your chest to people who understand and don't judge.
Good Luck Jess.