You should repost this in "family & relationships" section if you haven't already...
anyways, if I were you I'd show her my work, and tell her I have fun doing it, I'd also try to gain her trust and talk to her, tell her you know she's trying to protect you but at one point you'll grow up and there won't be anyone to protect you anymore.
If after all this she still doesn't want to listen, take your laptop and either go to your friend's house or maybe a coffee shop or a restaurant, somewhere that has free wifi and security and stop talking to her until you get paid, then show her your paycheck like a boss!
She will get mad because you disobeyed her, but she'll be proud of you in he inside and she won't show it of course.
One more thing are our parents divorced? How does your father react to having a genius son? maybe he'll back you up or if they're divorced you can spend some time with him and do your work.
And don't forget to apologize to your employers for the inconvenience