Something I've found made a big difference was the volume I have been playing at.
Being in a shared house, I've been quite self-conscious of playing, which means trying to be quiet... which means my notes are a lot less supported and consistent.
I've found it's worth making sure I'm playing at full volume, when I have the opportunity.
THIS was my number one issue. When I lived in an apartment this was a huge problem for my playing.
You might try going to the park and playing or a beach or forest near you if that's an option. Or play while walking on a busy street (Perhaps easier if you were in marching band) or rent a music studio or go to your local junior college and just sneak into one of the practice rooms. They're often empty unless it's around midterms or finals.
Also, I'll sound crazy probably but I think acoustics matter too. If you can be in a space that your instrument really fills the chamber and reverberates nicely it helps you feel the sound more and adjust your playing to get a more solid tone. What you're kind of doing is harmonizing with yourself. Parking structures are GREAT for this.
In short: Just go guerrilla.