I appreciate the honesty here, but I want to gently point out that you might be using the phrase "I haven't gone full nihilist" the way some people use "I'm not racist, but..." It sounds like a reasonable position, but the substance suggests otherwise.
Because here's what I'm reading: you've decided your actions won't meaningfully impact climate change (correct), therefore you're not going to orient your behavior around climate impact (okay), but you'll still live sustainably because it makes you feel like a good person (which is... essentially the same problem you started with, just reframed).
You say it's not about guilt anymore, it's about personal integrity. But personal integrity requires believing your choices matter - not necessarily for climate, but for something. And if not the climate, what? Your self-image? That's actually worse than guilt.
Here's my honest take: give your energy to the political fight. Actually. Not as performance. Join or donate to organizations pushing regulatory change, divest from funds holding fossil fuel stocks, pressure your employer, organize within your community. That's the work that matters, and it's way harder and less satisfying than sorting recyclables.
As for how you live day-to-day? Sure, don't be wasteful for the sake of it. But don't dress that up as some meaningful choice. Just live normally. You don't need your sustainable habits to feel good about yourself. That's the ego thing creeping back in. Do the hard political work instead - that's where the actual integrity is.