You may want 1 or 2
Havenwood Wurm 
as finishers
There are also low-mana cost suspend spells that you could play in the early turns, before you could have counterspell mana open, such as
Durkwood Baloth 
I think it'd be a bad idea to remove
Dewdrop Spy 
. From just looking at the list, it looks like that and the pestermite do the lion's share of the work with regards to actually winning the game.
I also don't really like the Winged Coatl, I suppose it's played as a removal spell 90% of the time? I guess that's okay.
It feels that if you want to actually play draw go, you should likely play more...draw spells and more counterspells. I know it'll cost a few tix, but maybe you should invest in
actual Counterspell 
s
At the very least, there are more counters that hit specific things, like
Remove Soul 
and
Negate 
and whatnot.
Other cards that might be worth considering:
Ophidian Eye 
Crookclaw Transmuter 
I would do something like...
Add:
4-8 more counterspells of some sort
2-4 bounce spells to "fix" whatever gets through your counter wall, cantrips would be best (
Repulse 
)
2 Havenwood wurm
[s]3-6 more instant speed draw spells, even
Sleight of Hand 
or
Opt 
- maybe not...
I'd remove:
4x Ashcoat Bear
2x Winged Coatl
2x Ambush Viper
Maybe also remove a hunger or a vines? I think those should probably stay though. In my opinion, vines is superior to Unsummon (except for with spellstutter sprite)
Of course, I could be way off base here...
Oh, I just thought of something.
Bonesplitter 
at 1-2 may be nice, just to give you a way to end the game quickly without needing many creatures.
