You are 14 and you are A/B cup - you are doing very well!! You don't finish growing til 18 at least, I didn't til 21, so I definitely wouldn't take WU for another couple years at least.
Just eat healthy and exercise and see what happens naturally.
I wonder who or what has made you think that this size is not big enough? probably the same media images that made me feel like i wasn't good enough.... when you think about it really, it is a load of rubbish. You can wear a push up bra if you want cleavage. And guys don't care as much about breast size as the media would have us believe. It is the shape rather than the size that is important!
I hope you don't spend the next 10 years hating your boobs, like I did. Life is too short!