Try using Stevia sweetner a natural plant. Cook with it and sweeten green tea with it. Avoid processed sugar and artificial sweeteners.
Erythritol is a good sweetener also. Less sweet than sugar but tastes good in tea.
Near zero calories and almost no effect on blood sugar and insulin. Supplies bulk and can be used with stevia. Evidence that erythritol has some benefits for blood vessels. No or minimal laxative effect unlike other -ols.