Naomi has two endings, you just have to make her your primary relationship (achieved by consistently taking Bully or Seduce options). Gluttony ending is triggered by eating everyone of the relationship options (encountered while dating them) before the third transformation.
Um, the only thing that I can think of is that you need to have eaten them before the final growth scene in the park to get put on that route. Other scenes in the uptown zone don’t matter, you just need to have eaten Naomi, Hart, Tiff and Jeff.
