Oh, those things. Flattening sports bras are your friend. Some qwearlings recommended a bunch a while back. If you are still feelings like they’re in the way, binding is also an option. Here is some information of safe binding. And guess what? This talented seamstress and lovely person is also offering to make binders for young people who can’t afford them.
Tailoring works wonders on men’s button-ups, and it’s not nearly as expensive as you may think. Find button-ups that fit in the shoulders and chest, and then have a tailor make adjustments. It will most likely be too long, so they can bring it up the length. And if the sleeves are too wide they can make those smaller too. This is usually all I get done for my shirts, and I love the boxy look they give me. This Ralph Lauren boys’ shirt I tailored for $30 remains one of my favorite shirts. Additionally, tailors can take it in on the sides below the chest to create a slimmer fit. More info that type off shirt tailoring here.
As for suspenders, try experimenting with different width suspenders and placement on your shoulders. If you bring them farther out on your shoulders they will make room for those guys. Check out the Qwear Suspenders Guide for more info.
Thanks for all the sweet words!