My mum and dad took my computer off me for 2 months because they thought I was addicted to it. What I was 'addicted' to was essays -_- I couldn't get my work done at home so I had to do it after school =[
maybe you just need to make her aware of 'how' you're using the internet. I mean she's probably worried you're doing something daft - you know like you hear about. my stepdad worries like that and I'm 21!!!!! Just let her see that you're not doing anything bad.