S.H.
Try Calvin Klein strapless bras.
They have several styles.
Go to Nordstrom or some department store.
They will help you with fit.
I have the Calvin Klein t-shirt strapless bra.
I like it and wear one everyday because I hate regular "strap" bras.
Just try Google searching "Calvin Klein strapless bras."
Oh and another tip: get a bra strap extender. Because if, you need one, then it makes it more comfortable and lessens the "sausage" roll effect because then the bra strap is not TOO tight but just right.
I got bra strap extenders for my strapless bras. And it lasts a long time. And then when I put on my bra, the band is not too tight.