One wouldn't particularly use a metronome a lot when learning a piece. It doesn't help learning the notes or dynamics, all it does is keep a very strict time (which often isn't appropriate!) for you to keep to that tempo on parts that you may wander with.
Listening to something a lot - or even hearing it subliminally - is a good way to 'get into' a piece. Apparently it can even work whilst one is asleep. A couple of my students used that excuse in class, but it didn't wash... But seriously, that's fine until there are different versions of the same piece. What happens then? I guess one decides which version and only listens to that. Similar to what a parrot may do? Not convinced it produces a musical rendition, and as far as understanding what's going on, maybe a non-starter. But - it appears it works for you, so please continue.
A concern I have is that when you perform along to the (presumably) recording, and keep in time, you consider that's it. Timing is exactly the same as that recording. I hate to say it, but so what? Where is the performance that's come from you, the player? You will have put nothing of that into the piece yourself, save playing all the right notes in the right order. Part of any performance should be putting your own stamp on it.
Don't get me wrong. It's a laudable feat to be able to listen enough then be able to play, but there is a lot more to performing that that. I'm trying to point that out!
So, don't worry about the metronome, for you, it's not needed, and shouldn't be used as a crutch or a big part of anybody's practice regime anyhow. Carry on with what appears to be successful, but consider moving past the 'that's got it note for note, so it's finished' syndrome.