Hiya natalie
my two were exactly the same i have male and female 6mths old now and my female was and still is a very little eater, i have changed there food so many times trying to find the right one in the end i found adult food she profers but they still have kitten dryfood aswell so they are still getting there goodness they need, it is really nothing to worry about she seems happy still playing and being a kitten, if you could see mine now he is a big boy and she so small and squany looking but she is very happy in her self and vets are not worried about her. If you do start getting worried then have a word with the vet.