Actually, they are called ‘personal floatation devices’ or PFDs, a specific type of buoyancy aid.
I am also rather, ahem, curvy, and only 5’2”.
You need to specifically search for women’s fit. Not everyone makes them or stocks them.
My favourite was bought from Palm. It was ages ago so I can’t recommend the same model but when I was looking, I did find their range to consistently be the most comfortable for me. I have a rescue one that I use in all circumstances and it is such a good fit for me that it is actually comfortable to wear and I don’t even notice it.
If I needed to replace it now, I would buy this one: Nora PFD. It is not by Palm but it is very similar in cut and style to my existing one. Palm Equipment Europe
On an equipment related note, I highly recommend this shop - Mountain Equip Co-Op - I have bought from them a few times and they ship to the UK.
Being short and curvy, I need bra sized swimwear to be comfortable. A bikini or tankini are better options than an all in one swimsuit. Or wetsuit for that matter. MEC sell neoprene shorts and trousers which are designed for paddling (they don’t ride down at the back) but I have also used them for other water sports. Always go for separates if you can - makes bathroom breaks and getting changed by the side of the river/road so much easier!