everyones accumulates weight differently, i'm 5ft 6, and when i was 15stone 12, i was a size 18. when someone else i knew who weighed about the same was a size 22.
i lost some weight and now im just under 14 stone, 13st 10, and i can fit into size 14 clothes. even though i know im still quite fat, so what im saying is one could weigh a lot, and the fat could be spread out..i dunno?? so ure gf could be a size 16-18 for all we know!!!