As a fellow person who is larger than I want to be, and it's mostly boobs and stomach:
(1) Don't wear clothes that are too small or squeeze into your old clothes that are too small. This makes you look bigger, and will chafe. Buy clothes that fit you now, even if that's just a couple of things that you wash and wear again, doesn't need to be a whole new wardrobe. Clothes that are fitted but that skim rather than cling are what you're looking for.
(2) Wear cycling shorts underneath skirts/dresses, or bodyglide/stick antiperspirant on the bit that chafes. Talcum powder can work too if you are sweaty. Life is too short to cause yourself pain from chub rub.
(3) Generally things that make me look slimmer are things that don't cling around my stomach - I am living in linen button-down shirts right now, with either chinos or jeans/jeggings. The shirts cover my stomach and the v-neck created when the top buttons are undone is flattering to my chest. Darker tops also make me look smaller on top/around my stomach. Dresses can be good too.
And finally (4) if you're not happy with your size, you can take control and do something about it - portion control, low carb, intermittent fasting, more water, more sleep if at all possible, move more in a way that you enjoy and that is consistent.
I am still trying my best on this, I keep reminding myself that I didn't put on weight overnight (though sometimes it seems like it!!) so I need to be patient and consistent. And I'm doing it for myself and my body, not for anyone else. We can do it!!