I think this is actually a good thing, though... you have something real you are trying to do, which guides you to what you need to learn.
I find it is a lot easier to learn in the pursuit of something I actually want to accomplish rather than studying in a vacuum.
So your approach, for example, is better than if you had just picked up a book on key and time signatures and started reading. You first tried to do something, ran into something you didn't know, so started to learn that thing.
True. I wouldn't have known I don't have the competency to sight-sing if I didn't try it first. That said, doing the "real thing" is out of my reach until I level up in other areas.
I’m curious if you have heard about Gnu Solfege. I just read about it here recently via the recent “Ask HN: I'd like to learn vocals, any suggestion on how I can do this?”
I find it is a lot easier to learn in the pursuit of something I actually want to accomplish rather than studying in a vacuum.
So your approach, for example, is better than if you had just picked up a book on key and time signatures and started reading. You first tried to do something, ran into something you didn't know, so started to learn that thing.