As others have said, it's not okay for your partner to be rude or shame you. If you feel comfortable, you should wear what you want.
However, there is something to dressing for the occasion. If you're going to a beach or a club at midnight and want to wear a crop top and shorts, more power to you. But regardless of size, it's probably not appropriate to have your whole stomach out at a restaurant or the school drop off. As others have said, there are ways to incorporate these trends in ways that suit your surroundings. For example, a high waisted skirt/trousers paired with a crop top where only a small strip of skin is visible, or tailored shorts with heels and a top or blazer.
I totally hear you on the floral/polka dot patterns though. It's something I noticed as soon as I came to the UK as it seems to be very popular with British brands. Sometimes you need to shop around until you find brands that suit you. I'm a 10-12 but an hourglass shape so flowy tops and dresses will never flatter me. And being petite with thicker legs, the straight jeans that are trendy right now just make my legs look like tree trunks. I've found what works for me and stick to it, only incorporating trends if they suit me.
Another thing to keep is mind is that a lot of fast fashion brands use very cheap, flimsy materials which don't do much for people that aren't stick thin. I've found I've had to change where I shop as I get older. I know we're all struggling with budgets at the moment, but if you're not bothered about following every trend you don't need to buy as many clothes, so it may be worth spending a bit more on fewer, better quality items.