I think One with Nature, Whirler Rogue, Awakening Zone, Behold the Beyond, Shamanic Revelation, Bow of Nylea and Bident of Thassa would all fit your deck very well.
Sundering Vitae is similar to Naturalize, but looks a lot better in the context of your deck.
I am not sure if Downsize, Reclaim, Primal Growth and the 1/1 fliers with no other abilities are quite good enough. Also, in your low curve 2 color deck, Chromatic Lantern seems unnecessary, Simic Signet is probably better if you need the ramp at all. Dissipate is expensive at 3 mana, i would play Unified Will or Arcane Denial instead.
You might want a couple of ways to answer an opponent's creature in case it becomes too threatening. Consider Pongify, Rapid Hybridization, Reality Shift, Lignify, Control Magic or Ulvenwald Tracker.

This is something like one of my own creations except the commander is Edric. Here is a list of cards that I think will be great in your deck, and links to my decks for more.

• Spies

AEther Figment,Cold-Eyed Selkie, Den Protector, Dryad Sophisticate, Escape Artist, Flitterstep Eidolon, Lu Xun, Scholar General, Looter il-Kor, Metathran Soldier, Thada Adel, Acquisitor, Thalakos Seer, Thalakos Sentry

• Pump

Scytheclaw, Quietus Spike

• Tokens

Fungal Sprouting

• Links

Edric Makes Your Opponents Wanna Fight Each Other

Edric, The Greatest Spy in the Multiverse

Happy gathering!

Try adding Sword of the Animist and Harvest Season because ramping is the best.