You don't need studio monitors to mix and master, lol. I (and MANY other people) do it just fine on normal headphones. It's more about learning how mixing works over time. It is a gradual process, but worth it in the long run. ;)
Also, you have some good ideas. If I may, some things you could work on:
- Use more stereo! Your tracks are very "close" sounding at the moment, spread em out!
- Don't have melodies that play constantly. Insert drum breaks, sfx, etc. - mix it up. ;)
- Use more sub! At the moment, many of your tracks have very little under 200hz, which means basically no bassline. You'd be surprised how much this can change a track.
Overall, though, you've improved a bunch since you first got into this stuff. Keep it up! :)