Try 10C. C is one of smaller cups, especially with band 10. Many people think C and D are big cups! but it's a myth - unfortunately still popular. Don't give in to letterphobia!
10C is easy to get, so it's no problem for you. Read How to wear a bra. If your boobs are bulging, ask for D cup and don't care about letters*.
It's quite possible that you'll change your cup to bigger
Most women should wear D-G cups. If you can imagine Gaussian distribution, these cups are in the middle, left are D- and right G+.
But the most important is band size, because it's responsible for support and pushing up. If band is too big, boobs don't have a shelf to lie on it.
Calculator which you posted said:
We are unable to find a size based on your measurements
I looked at their chart and I know why - they stop on E size. It's definitely not enough. They also give too loose bands.
This pink calculator which I posted allows you to have f.e. 50 cm difference without any stupid comments. And - what's most important - it gives right band size. Band is basic!
Plus for Hestia for It is important to remember to have a very FIRM, SNUG underbust measurement. But they have to learn many many many things.
* I know a woman who was wearing shoe size 40 instead 42 for many years, because she thought 42 is a shame (!). Now she wears 42 without pain and deformation and she doesn't know why she thought 42 is sth wrong
I don't have this problem and I wear shoes 42 and bra 30J. Sizes like every else.