Artist, Did not register business, made some sale through art gallery, should I stay as hobby or file schedule C ?

Hi All, Besides my day job (W2), I am also starting as a professional artist (selling paintings)
I did not register my business last year, as I only sold through art galleries (for-profit and nonprofit).
My income through art sales are minimal, but expenses are high ( art studio rental, material, etc.).

Should I file art sales as a business ( Schedule C) even if I have not registered a company with the state ( and no direct sales)?
I will be reporting losses. Or should I report the sales income as Hobby and not take the loss as a deduction? Galleries will not send 1099.