hit the gym, do some military press, problem solved. the male figure should resemble a V, not a prefect rectangle.
I forgot the brand I wear, but it's pretty slim. I just don't like how shirts pop out from your waist when you tuck them in (makes you look like a mushroom). No idea if they're dry cleaned or washed because I have someone that does that for me, but I'm pretty sure it's washed. I'm pretty skinny 130ish at 5'7" so anything baggy will make me look shorter and, well like dude on the left. But that's only to work though, it's really not all that comfortable wear everything super fits you. I wear loose clothes outside of work. Didn't know the norm is to use v-necks with a long sleeve. I guess it doesn't really matter because I have to wear a tie to work so the collar is always buttoned up.
It's not fashionable to wear a t shirt under a button down shirt. You don't see undershirts in fashion forward places like NYC, Milan or Paris. Wearing a t shirt under button downs is bro style. And most bro's fashion sense involves them wearing Affliction shirts at the club and wearing Crocs to dinner. The only button down shirt which can somewhat properly be worn with an undershirt is a solid white button down, but it's a fashion faux pas to wear it with any other form of colored shirt.