Well, I can say that your composition skills are accurate and good. The sounds you picked are pleasant.
However, it sounds like you are using triangle waveforms instead of square waves. Square waves would sound more like a real chiptune. The triangle waves you use are also way too high of quality, so my ears know right away that it's not authentic chip.
You could easily replace the instrument you used with a square wave generator. Or just change the osc to square in whatever VSTi you used.
It is true that the NES had a triangle wave on one channel, but it was highly distorted and had a very unique sound that is very hard to imitate. It is not the same triangle wave as on a standard synthesizer.
Again, I think you did a good job with the composition, and the tunes sound cute. But if you are wanting to get an authentic sound, I recommend one of the many wonderful trackers out there like Famitracker: http://www.famitracker.com/
Free to download and use. Plus it is set up to give you authentic NES music, and you can even convert your song to play off a Nintendo cartridge. Of course there are many other chips and sounds to imitate out there and they all sound different and unique.
I like Sega Genesis personally. I have a tracker (VGM Music Maker) where I make authentic tunes for it. Someone even played one of my songs on an actual European Sega Genesis (MegaDrive).
If you enjoy your music the way it is, that's cool too. But my initial thought is that you are wanting to make authentic sounding chiptunes. Is that your goal?