when I should change iPhone

[losting]

I'm sorry to ask how to choose a mobile phone, or when I should buy one. I've been using my current iPhone for almost four years, and there's no sign of lag, but the back is broken, the storage is not enough, and I'm paying extra iCloud fees every month. There's also a tariff system, so I don't know whether I should change my iPhone now or wait for the new iPhone 17 series to come out, but I'm afraid that the iPhone will become much more expensive because of the tariff.