Some people with breasts do want them to be smaller, or don't want them at all - I think there is a common cultural idea that "all women want large breasts" (or "everyone who finds breasts attractive likes larger ones better") but just like with any other generalization about people's bodies or sexualities, that's never going to be true for everyone. There isn't anything wrong or abnormal about you wishing you had smaller or nonexistant breasts.
I'm sorry to hear they are stressing you out! There are some options for minimizing the look of your breasts that might sound good for you. Some people prefer to wear a sports bra over a "standard" type of bra because that tends to flatten the breasts down a bit, and there are also binders, pretty commonly available online, that will significantly flatten the look of your chest. Do either of those sound like something you might be interested in trying?
As a note about binders - there are safe and unsafe ways to practice binding, so if that is something you look into, make sure you're using a true binder and using it according to directions and not using something like compression bandages or other unsafe methods.