What I am lacking is the ability to create compelling photography but that is a process independent of technology.
I can go on and on and on about how I learned photography with just a 55mm f/1.8 and a 135mm f/3.5 prime lens. I can go on and on and on about how the 55mm taught me to work within the limitations of the focal length, i.e. DoF and FoV. I can go on and on and on about how the 55mm taught me about angles and moments. I can go on and on and on ... but I won't. (Chorus: "Too late!")
I always challenge people, who want to really learn photography, to pick one prime lens and shoot straight to JPEG for three months. Everything, one prime lens in JPEG. Do it!
What's funny is that while I'm on the other side of the fence than you are... that's is practically what I did. I hate the 18-55 and the 75-300 so much that I wound up using only the 50mm f/1.8... though I did it negligently... which is to say that I knew I liked the images so much more with the 50mm that I just shooting away without knowing the technical aspect of what I was doing... So there's that.