What you describe sound like insight practice to me, and I thoroughly recommend bringing this into daily life, but a few tweaks could be made which can, hopefully, allow you to make quicker progress.
I try in everyday situations to replace my thoughts by a form of awareness.
Awareness is what's there already, thoughts are just objects arising and passing away so don't try to "replace" them; acknowledge them, observe the Three Characteristic in real-time and move on. Remember, if you can see it then it can't be what's doing the seeing.
I try to develop the sense of an observer to replace the sense of an actor.
Rather than doing this, pay attention to which sensations imply that there's an observer there in the first place.
I pay attention to the movement of my hands and try to notice that I'm not actually conscious of every movement that I do.
This is an insight in itself, you're seeing impermanence in a really clear way here. Remember that you can't observe two things at once, insight practice shows this to be true so perhaps try just noting when you're aware of the intention to move, and then the movement itself. When you're not aware of this, what are you aware of? Note that!
When the feeling of controlling my hands reappear, I close my eyes two seconds, pay attention to the "blackness" and open them again.
Why do you close your eyes? Did you notice the intent to close your eyes? Did you note "blackness", or the intention to open them again? Note everything that appears in awareness.
Then, I pay attention to what my hands have been doing when my attention was away from them and how even if I'm aware of the current movement, my intention is subconscious.
So, you're looking to the past for insight rather than investigating what's going on right now? Be aware of the current movement, not what's gone before, not what might come next. Be immediate.