Why dont you discuss it with your parents again and ask them what they would consider fair.
Most people continue to live at home or move back home as they either cant afford to move out or they are saving etc. Maybe to get their own place.
Any people I know still living at home, and indeed myself when I lived at home, paid at most about €100 a week. This was when I was in my first job out of college or based on the notion that I was saving for something.
It really depends on your own financial circumstances and that of your parents.
For example if you were lucky enough to be earning €50k per year or more I would think that €100 per week at home would not be enough.