If underneath my breasts measures 36 inches and around my breasts measures 46 inches what bra size doe sthat make me?  It's really confusing and I don't think I have ever had a bra that has fit me properly

I think I am am a 36H but as I have never been measured properly I could be completely wrong.  I would love to have a pretty bra that also gives loads of support but the bigger bras tend to be very plain or like something your great grandmother would have worn!!! Also why are these bigger bras so expensive compared to ''normal'' sizes - ...