The melody feels pretty aimless for the most part, probably the most important part for most chiptunes especially with the limited polyphony that old game systems had(albeit you're not staying within those limitations here, people still generally expect a strong melody from a good chiptune). Actually forcing yourself to compose more within the limits of an actual NES or gameboy song can make your chiptunes more interesting, it forces you to use more arpeggios, riffs, and counterpoint instead of sustained chords and of course to work on the melody more. Try limiting yourself to 5 tracks, one triangle, 2 pulse waves, sample, and noise. Tasteful use of portamento and vibrato also help a lot, if you listen to some of the great chip soundtracks like MM2 or Pokemon RBY, there's a lot of expression in those square and triangle waves
I'd also highly recommend learning a more traditional tracker like famitracker or even just using samples inside modplug or [insert tracker here]. I tried using that program for a few minutes, it's really slow using a mouse based tracker, once you learn your way around the keyboard it'll be hard to go back. There's an added benefit that there are thousands and thousands of source files out there that you can look at, it's nice to be able to look directly at the data for some of your favorite songs. It's also just really cool, I love listening to music inside trackers and watching the lines of code fly by