How do you practice when you can't tell if it's working?

This is more of a psychological question but if you have technical tips I'm open to that as well.

What I mean is, with singing, I really feel like I have no sense of whether I'm getting anywhere. I know that I've learned stuff over time and gotten better but it's hard to define and any given practice session can feel pointless.

With playing guitar for example, I can get immediate feedback as to whether I played the right notes, whether I played a piece without messing up, etc. I can practice and immediately know what I got better at.

With singing I can't even tell if I've sung in tune unless I record it and play it back, and I can't really tell at all if my tone or other things sound good because, well, I guess it's common to hate the sound of your own voice. My recordings of my voice *always* sound bad to my own ears.

I'm trying to finding a voice teacher, and hopefully that will motivate me in the sense that I don't want to waste money, but I'm also worried I will still feel like it's pointless (even though I know it's not).