[Measurement Check] Have always worn a 10A (32A) but just used the calculator and it says that I'm a 6D (28D). Can this be right? Witchcraft!

I finally got around to checking out this sub after seeing it linked everywhere because I had a problem with my bras where the cups gape at the top. If you look down you can pretty much see everything, and my bra also stands away from my body (if that makes sense) so there's a pretty clear line when I wear tight fitting shirts.

The calculator said I'm a 6D! I don't think I've ever even seen a bra in a store that small! I don't I don't have much going on in the way of boobs but wow!

Anyway, I thought it best I get a second opinion (or two!) before investing in giving this a go. My measurements are below. Also, if anyone knows of a good not to expensive place to get a bra in that size in Australia recommendations would be amazing! Thank you!

Normal Underbust: 27 inches
Tight Underbust: 27.5 inches
Standing Bust: 30.5 inches
Leaning Bust: 31 inches
Lying Bust: 30 inches