Helppp!!

I recently started giving my 11 month baby pediasure but also giving her formula in between so she woudnt just get use to pediasure. Now all she wants is pediasire and not formula I give her formula for 1-3 yr old ( doc said it was fine ) but pediasure is to expensive for it to last only 3 days and about 3-4 bottle feeds a day depending. Idk how to correct this because she is only drinking pediasure and not formula