Yeah, thats rough. Can I ask how old you are, to start?
When I met my wife, I was somewhat skinnier (~260-280) and feeling good about my body having just lost nearly 100lbs (this was before gaining it back and more, and losing again, but thats another story), and when my shirt came off the first time, she was the one taking it off for me (
), so presumedly she was ok with whatever she potentially might see underneath.
But, I sort of resist taking my shirt off around anyone else -even my immediate family. No one in my wife's family has ever seen me with my shirt off, I don't think. Last week, I took a big step. 2 of my younger brothers (as well as my 19yo brother's HOTT 18 yo gf), and my wife, went to an amusement park/water park. I decided I wasn't going to be one of those people who wore a T-shirt around all day at the water park, so I just went shirtless, as if it was no big deal. I knew my brothers wouldn't care and if they did, I don't really care what they think anyways. I thought I noticed a couple glances in the general direction of my gut from my brother's girlfriend, and some occasional giggles every one in a while from some teenage girls who happen to walk past (who knows, they might not have even been laughing at me). For the most part, I'm at the point where I just don't care any more. I don't need to impress anyone with my physique, I've already got my wife and she presumedly doesn't really care what my gut looks like, so why do I need to care what anyone else thinks about it? I more wanted to get some tan on me, and not feel restricted all day in a wet T-shirt which lets be honest, is every bit as revealing as if it weren't there at all, except for maybe hiding the stetch marks (no doubt I have many more than you or anyone else). And really, at a place like a water park, bigger people have more company nowadays anyways.
As for you, I can see how your situation is a bit different. You sound like, if your gf hasn't seen you with your shirt off, you're still in the period where you're still trying to impress her. You definitely want to impress her family, that really never goes away. I still try to impress my wife's family. I think, at the cottage, like if you're going swimming or something, casually taking your shirt off before jumping in the pool isn't going to turn any heads. Even though we think we can hide our bodies behind our clothing, I think people really know what to expect to see when the clothes come off based on how you look with the clothes on anyways. But, no one is saying you have to walk around the whole time with your shirt off, either, if you're uncomfortable. I mean, I think for the most part, your gf might have some interest in seeing you with your shirt off, but I don't think her family will really care. I mean, they won't particularly care to see you with your shirt off, but they won't be like, "oh god, I hope he keeps his shirt on" either.
Actually, might pose a good opportunity for you, if your gf sees you with your shirt off, ask her when you get to see her with her shirt off
I bet you anything the answer will be a playful slap, followed by "Its no big deal for a guy to take his shirt off, but its a bigger deal for girls". She's probably more nervous about taking her shirt off in front of you!