One piece swimsuit for wide shallow breasts?

[rubybleu]

This year I really want a one piece as we have a fairly active summer holiday planned.

Trouble is, every one piece I've ever tried on flattens my boobs sideways so I look like a 10 year old with a tummy.

Has anyone with this problem found a nice flattering one piece?

Sainsbo swimsuits tend to be quite supportive, or if you've got a bigger budget, you could try Seafolly (I've only tried the former, but have heard good things about the latter!).

I don't understand why your previous swimsuits were flattening your boobs. Aren't you buying bra-sized swimsuits, or swimsuits with moulded bust panel or underwiring?
If you're buying swimsuits which are just a piece of tight fabric over the boobs, then that's probably the problem. Only teenage girls and those blessed with perky boobs can get away with those.
Something like this from Moontide perhaps?
Basically anything with built-in bust definition.
If you have a belly, I find that ruching and a small print camouflages better than flat, plain colours.