Welcome in here!. It looks like You have talent indeed.
Here there's an After 9 Section for "bolder" art which comprises, more or less, nudity or more impressive or violent images, always within some sort of decency limits, I guess. In the case of your sketch, my personal view is that the "message-intent" is certainly still in the art domain and, although erotic, not pornographic, however we may define it. Nonetheless the content may be classified as "adult", since probably it would not raise a spontaneous interest of children or an image they would enjoy, understand or appreciate in particular.
Personally nudity in itself and even a mild erotic content in art is normal to me as an Italian, thus well accustomed to that in many classical artpieces we've seen all around us since 6 or more centuries, and I would hardly see a Tiziano (Titien) nude as a threat to children or offence to someone, especially in these days with extreme form of provocative art or violence or "transgression" occurring everyday and everywhere in the world.
Nevertheless I understand some sort of artrage customers shared boundary had to be found by our Artragers.
Panta rei (everything flows)!