Shape underwear advice please!

[SandraTheBee]

I have just bought myself a tighter firing/bodycon type dress. I don't usually do dresses but this looked really nice on.
I am thinking about what to wear underneath.
I am a size 6-8 and pretty flat chested, but still would like a smoother silhouette especially round the hips and bum where I suspect my usual underwear would spoil the look.
Any brands/ tips gratefully received! All i know about is spanx but I think Primark do some of their own?

I have this tuclothing.sainsburys.co.uk/p/Secret-Shaping-Black-V-Neck-Slip-Dress-Light-Control/133766149-Black?searchTerm=:newArrivals&searchProduct= from Sainsburys. It doesn't ride up at all and you forget that you're wearing it.

I've had primark shapewear and it's been decent. I go for the "wear your own bra"-type body, gives a very smooth line. I wear it over tights and pants, as from experience I know that the popper crotch would be uncomfortable next to my skin. HTH