Black/Blue Poison Proliferate Deck

[fezkid34]

Here's an idea for a Blue Black poison proliferate deck.
I realize i need more poison counter cards, so i need some good ideas for what i should use. (Try and keep suggestions standard im looking to enter some tournaments with this deck)

CREATURES x12
Thrummingbird x1
Pierce Strider x2
Oculus x2
Fume Spitter x2
Psychosis Crawler x1
Phyrexian Rager x2
Signal Pest x2

INSTANTS/SORCERIES x17
Steady Progress x2
Virulent Wound x1
Spread the Sickness x1
Vivisection x2
Cancel x4
Negate x3
Essence Scatter x3
Shape Anew x1

ARTIFACTS/ENCHANTMENTS x11
Contagion Clasp x2
Contagion Engine x2
Phyresis x1
Corrupted Conscience x1
Mind Control x2
Trigon Of Corruption x2
Voltaic Key x1

LAND x20
Swamp x7
Island x13

SIDEBOARD
Stabbing Pain x1
Assassinate x1
Doom Blade x1
Negate x1
Essence Scatter x1
Steel Sabotage x1
Instill Infection x1
Vedalken Anatomist x1
Last Kiss x1
Myr Sire x2
Skinwing x2
Bonehoard x1
Flayer Husk x1


Any suggestion would be nice, and keep in mind that this deck is made of only cards i currently own, so I want some suggestions on what i should buy to put in the deck and what I should take out to make room for better cards.