I have small boobs. B-cup (if I’m lucky!) and 32-34 depending on the bra. I don’t really need a bra I suppose but as the years go by it gives me a bit of extra lift and shape 
I have NEVER had a strapless bra that I have felt good in. My major grips are that it either cuts in too much at the top of the cup so you get this sort of indent rather than a smooth line or that my boobs just seem so low! Like there’s no decent lift without the straps.
Any recommendations?