my MIL plan was also, she told me that she want 2 buy my walima dress, but i spoke 2 her and told her "Dear Ami apne Nikkah ka dress select kia tha ab mera turn hai". Forget the idea 2 do shopping with ur MIL i can say by experince that ur MIL will do what she want it doesnt matter whether what u want. but i wish that u get a chance 2 select what u want.
My fiance and i are vey close. I can get stuff done through him:p