I'm 5'2", and during the times I have weighed 9st - 10st, I have been in size 12 or occasionally 14 tops - but I hate wearing tight and close fitting stuff. I don't have big boobs at all.
I am currently about 8st, and in size 10 or 8 generally. When I weighed 7-7.5st, I was in size 6-8s.
That makes it sound like my weight has been all over the place, but really I have just gone from being very very tiny and skinny pre-kids, been pregnant (highest weight was 10st4oz) and then back to somewhere in the middle again!