Time spent v progress is not a good bench mark in music. Musical knowledge and skills to not develop hand in hand at a consistant rate, it is like a cumaltive over spill, you just keep on filling up with info till spills out, learning is a series of plateaus that level out for long periods before you leap to the next one.
So exactly how long and what you been working on is more to the point.
All the usual things are available to work on, interval training, chord construction etc, but also listening to music and hearing what is happening is more important.
Correctly identifying what you are hearing, why it is happening and what it is it about its use in this context that works (or not) in what you hear.
As we get older we become more experienced and build up an "inner library" of sound to relate to. It not so much as identifying the individal notes you hear but there relationships with each other.
Jailhouse Rock, by Elvis the intro is two notes a semitone apart.
The first point is they are a semitone apart, hearing that is the priority. Whether it is B-C or E-F or G#-A is the use, but the relevence is it has to be, and always will be semitone apart. Everytime you hear that intervalused in a song or piece of music you relate it to something, in this case Jailhouse Rock,....you hear JailHouse rock in the music, you make a comparison and come to a conclussion within a split second that what you have heard is a semitone because it sounds like Jailhouse Rock (you also compare it to every other song you have recognised it in to support the idea it is a semitone)
Walking on the Moon, by the Police, again the intro, but this time it is a tone apart, so if we hear that in another song we can assume what we heard was indeed a tone apart, so it is added to our inner library as one reference we will use to confirm that what we heard within a song was indeed a tone apart.
James Bond Theme, that intro is now many things, it has a tone in it, a semitone contained in it. But because it uses a 2nd and a b3 from its root so it is a minor 3rd, it is the first three notes of a natural minor scale, so it is also the last 3 notes of a major scale (6-7-8), it is use in songs/music such a Babylons Burning, Hall of the Mountain King, etc etc all confirm and use those intervals in some way, so my inner library know what they are and how to use them.
It not so much what notes they are, that relationship is relative to the use. So in music we have those with perfect pitch, these people can not only hear the interval and use, but the notes within and work it out.
Then there as those like me, who have relative pitch, i need a note to relate to, then i can work out where the interval sits, so what notes are being used, by i need a note to relate it to.
So on a piano if you play a D and ask me what the note is i am guessing, but play me a C first then play a D and i am telling you for sure what the note is. So long as i can hear the that C in my head i can build a relatioship to other notes.
So that C-D is Walking on the Moon,(amongst many others) its a tone. Play D# and i will in my head hear that James Bond theme and every song or tune i know that is a minor 3rd confirm it is a minor 3rd.
So if it is a minor 3rd i can work out the individual notes being used in relation to the root.....and so much more in the relationships with in the song/music.
So it takes time and practice, but it needs you to "hear" these things, so that means listen and identify them and add them to your own inner library for you to reference. Some of my refrences ma mean nothing to anybody, but the intervas and notes they may lead to is familier to all.
LOL on the radio now White Wedding by Billy Idol..the into is a minor triad, so 1-b3-5-b3, then it drops a tone, then drops a IV, so it is in effect a V-IV-I progression....now i am in the area i need to be if i want to learn it.
Fact is i just have learned the intro because i cannot un-learn what i have heard, that intro is in my inner library as another reference for me to use. Like i said it takes time and experience to learn to "hear" these things, listening to something is not the same a hearing it, we have a peripheral hearing, so we hear lots of things, but focusing it to hear certain things is a skill to be learned, but once developed it takes care of itself, bit like walking will take you where you want to go, this will lead your ear to things.