The pottermore sorting quiz can have different results depending on which questions you get. Most of the people don't only have traits from one house, but from all of the houses, so the results can vary there. There are different things you can do to define your house. You can either choose the one you think suits you better (The harrypotter.wikia.com/wiki/Sorting_Hat (harrypotter.wikia.com/wiki/Sorting_Hat) would consider your preferences after all), choose the one that you got first (saying that you can only be sorted once) or take all the questions of the pottermore quiz on a different site (This would be the one I found, it also gives out the percentages of the houses you are: gotoquiz.com/pottermore_sorting_quiz_all_possible_question (gotoquiz.com/pottermore_sorting_quiz_all_possible_question) I don't know how accurate they designed it, though).