My mom is trying to plan my “wedding”

Idk what to do. I’ve never wanted a wedding. I have terrible anxiety. Me and my fiancé are about to sign the papers to be married because neither of us want a wedding. I decided I wanted to buy a cute casual white dress and buy out daughter a pretty dress and take pictures so we can have that as a memory at least. I didn’t want anyone there for that really because I don’t like being stared at. I can’t get comfortable and won’t be able to take good pictures. My mom completely freaked out when I told her we’re not having a wedding or a ceremony or anything. She begged me to be there when we sign the papers and for the pictures. She’s trying to make me invite all my siblings and there’s 6 of them. It stresses me out bc I don’t want to upset my mom or my siblings. I have thought about just inviting the sibling I’m closest to but then all the rest will be mad. Also my husband is not into dressing up. That’s just how he is and I’m fine with that. He said he could buy a black and white flannel or grey and white flannel and black jeans or something and I thought that would be fine. Well I told my mom that and she freaked out again saying that Will loook stupid and he needs to wear a nice shirt. What are your thoughts on my ideas.