I'm older now (55) and grew up in a time period where if you didn't have a bikini body, you didn't wear a bikini! I was always very thin and *could* wear a bikini but never felt like I looked great in one as I was kind of a stick. I was/am always more comfy in a one piece or tankini.
Honestly, I *don't* care what others think of me but I'm still of a mind that if you have a fat gut (and I've got one now), I don't want to have it out and exposed. That's just me. I'm not into it. Many people don't care. I've seen huge women in bikinis. They don't bother me. I'm in awe that they don't care. I just couldn't do it myself.
So, OP, wear what you think is comfy. Most people won't care about your pooch, but if it bothers you, YOU might feel self-conscious all day.