What to do when im shopping with ... ?

My mom .. Lol . But whenever i go shopping with my mom , she ALWAYS puts down whatever i want to buy.. I tell her i buy it with my own money , because i think its really cute but she always has to say sh*t . It bugs the AF outta me .. Like ill tell her ill buy this shirt and she goes " oh no youcant buy that shirt , why u buy that shirt !!?!?!?!? " and yells it .. Yet she shops at a&f , hollister , aeropostale and some of the stores I shop at , and im 15 . I mean i love her , but what can i sayto her ? Because i hate it when i go shoping with her and she spazzes .. Thanks .!