i hate receiving christmas/birthday gifts

it’s not really that i hate the gifts, i’m just not very expressive and i’ve been told i look very sad or upset, when really im just overstimulated and don’t like pictures and my smile always looks very forced. i’ve tried to explain this multiple times but my family won’t listen, and a lot of them just assume i hate my gifts, even if i thank them. Christmas stresses me out so bad because of the gifts, why can’t i open them privately and then thank the person later?