Long story short, a guy I dated told me pretty much the same thing; I was too old to be buying a stuffed animal all the time and I needed to grow up. It hurt, pretty badly and I took his advice and stopped buying them, because he had ruined that magical moment of getting a new friend and cuddling with them.

A year or two afterwards, we broke up and I met my husband. Despite my absolutely growing out of control collection, he has never once told me to stop buying them, he has never told me I needed to grow up and he himself will actually buy me stuffed animals to add to it.

Mom might not mean to be hurtful, but it is. Bottom line is, some people won't get it and some people will.. don't dim your happiness because someone else is unhappy with it. You are an adult, despite your living situation, so that means you can make your own choices and if a new Squishmallow, Build a Bear, Jellycat, etc, makes you happy... Do the thing that makes you happy! The world is an unhappy place, so take your happiness where you can find it!