Ok, I mean this as a compliment here, even though it would sound kinda rude in any other context. You look like any other chubby guy I'd see at a waterpark. I wouldn't even look twice unless I already knew you or got a close up of the scars. And even the scars aren't that bad because they look like your pec line from a distance. I had to click on the pic and look at it again to really notice 'em.
In this case, I think the extra weight might help you. It makes it look like your swimsuit is sitting high because it's a bit too tight, not because you have "girl hips." You might also be able to explain the scars as removing some extra skin after losing weight as a kid. Most people these days have seen shows like Biggest Loser where there's all that nasty skin leftover. Kind of a gross excuse, but I doubt anyone would question it and suspect you're trans instead.
I really wouldn't worry too much about it. All that chest hair is gonna make people think "male" the second they see you. Even if someone does think your chest looks odd, they're still gonna think you're just a dude with a weird body. Cisguys come in all sizes and shapes...and I've seen some with weirder nipples than most post-op FTMs.
