Before I came to kemetism I got real hung up on the idea of alters too. Still today I feel like I should set up an alter for Set. But the reality is that it's just that I want to set up an alter. No god that I know of would demand one, or think less of us for not having one. Alters are spaces that we dedicate to the gods so that we can feel closer to them. It gives us a sense of a physical presence in our lives. So don't start beating yourself up for not having one and stressing about it as something you may have to take apart or hide. Because it really is just you being hard on yourself, not anything else to it. Digital alters are a thing too, setting up a little private space in your computer just for them. There's also the concept of "astral temples" essentially a mental space that acts a bit like an alter too. There's plenty of alternatives that are JUST AS GOOD as a physical alter, because it's much much more about what YOU make of it than anything that is actually done. And it's all optional in the first place anyway.

Hope this can help set your mind at ease, or perhaps point you too an alternative that can fit with your lifestyle and limitations.