I can't find any links to your Wild Magic system in the Table of Contents, so could you explain how you're limiting it? As it is, it looks like a first-level bladeweaver with decent rolls can cast 1d6 damage spells all day long, while a first-level wizard with the best rolls possible and a racial bonus gets 3 1d4+1 spells and 3 1d3 spells.
A few possibilities:
*Doesn't Always Work: A wild spell has a 20% chance of doing nothing.
*Unpredictability: A wild spell has a 50% chance of doing something other than what was intended (selecting target randomly, inverted effect, curdling all milk in a 50-foot radius, etc.)
*Powered by Luck: Each SP spent inflicts a -2 luck penalty to all rolls in the next round, to a maximum of 10/round, at which point the penalties start carrying over into the round after that.
*Overchannel-style Backlash: Each five SP spent (rounded up) inflict 1 damage on the caster.
*Paradox-style Backlash: Each SP spent gives the DM a point that can be used on an effect against the caster.
*Wild-Touched Mind : Each spell calls for a Sanity check (see the online SRD for the sanity rules), with a potential loss of 1/1d3 for every 5 SP spent (round up).