Prix,
Your leak is minimal........but perhaps the dreaded "clogged PS solenoid screen" syndrome is occuring. this makes your steering stiff.....
Your original post stated the car just "pulled " to the left, so perhaps I misunderstood - this, to me, doesn't mean stiff steering. But if it truely seems "stiff" when you turn the wheel, that is a different issue - the PS solenoid issue............
Run a search on this subject for further info.....
If your tire wear is consistent (no cupping, edge wear, etc...) , and they are inflated properly (*and evenly), they probably aren't the problem.
For me, you have a 11 year old car with no previous maintenance to the PS unit. This means the fluid is extremely dirty, likely to clog, and likely to cause leaks & stiffness.