I can see where you were going with it. I'm not sure if FL Studio doesn't allow you to use VST's (I have never used it personally) but you're really limiting yourself when you're not using them. If it is FL studio thats holding you back its time to move on. You have potential that is too good to waste. You can find so many free VST's that have excellent sounds for chiptune music, you just have to dig a little in google.
www.tweakbench.com is a good place to start. I recommend these VST's to get you going with this song specifically:
Peach - Synth
Toad - Drums
Monomate - Bass
They are all free and really easy to use. Give them a shot. They can only help you make your songs better.