Buying online is hard!!!
Usually in mat clothes I am a size 12 (kmart tops, skirts, jeans west jeans). I am big busted but short so often find them quite long and sometimes baggy in some places.
Asos I purchased
Size 12 blouses - pretty good but will def last me for most of my preg as roomy
Size 12 tshirts - bit big around my back but will be good in last few months
Size 12 dresses (bodycon and flowy styles) - bit big on flowy ones... would prob have got a size 10 in hindsight.
You can return easily if its an issue.
Def go a size 10!