I suppose it´s really marie Louise. There are portraits, where she looks different, but it depends also on the artists, I believe. This picture is also presented on the page of the Glauco Lombardi museum, which dedicated to Marie Louise of Parma and her descendants of the Albertine line, and they say that is her. On other pages there was sometimes said it´s her mother, but I don´t believe this. She really looks differently.
About the nose and the lips. I don´t think, that these features only come from the Bourbons, I think Leopold II., son of Maria Theresia had also a bit this appearance. I have different pictures, where he reminds me of this kind of nose and lips of his descendants!
But it´s not to forget that Franz Stephans mother was herself a Bourbon Princess, Charlotte of Orleans....