Chubby girl in bikini?

I have a pool party tomorrow. There will be boys there and I am kind of chubby, I am slim I think but I have a flabby and chubby stomach. Would I look fatter in a one piece/ tankini or a bikini. Every single girl there is extremely skinny, like model skinny. And since guys are there I don't want to look like a total cow compared to them. So would I look better in a bikini or one piece? Oh and I have never worn a two piece and I am uncomfortable in them.