I have an extreme fear of vomiting?? my life is being ruined?

It's called Emetophobia, it's quite common and there is treatment available. You will need to go to the doctors thought regardless of your Mum's opinion. You are 17 for crying out loud, she can't stop you going to the doctor! Just go and get it dealt with, right now it is controlling your life and will only get worse. You must be missing out on so much, you should be out and about having fun, not worrying yourself about this.