VorcyWomen Tummy Control Shapewear High Waist Butt Lifter Body Shaper Knickers Thong Panty Shapewear

I’m a size 10 and really not sure which size to go for as could be small or medium but don’t want too small or too big thanks

What size for size 16 ?

What size should I buy if I’m at 16/18?

I’m a UK size 12 - is the S okay or is it too tight?