Hi
Firstly, why did you register under GST? Looking at your turnover, you were not liable for GST registration.
Since you had registered, you are liable to file monthly return GSTR 3B and quarterly return GSTR1. GST has to be charged at 18%.
From where do you receive the YouTube income? And in which currency? It could be classified as export of services. Had you filed letter of undertaking under GST? If not, you need to pay GST on such income and then claim refund.
We may discuss further over this.