It looks like you are getting good advice here. The most common cause of pulling is a tire. Eliminate this possibility by swapping the right and left tires (one end of the car at a time) and see if the pull goes from right to left. If so, it is a bad tire. Different pressure left and right (as mentioned) can do the same thing. A dragging brake can cause pulling too. Check that by feeling the wheels to see if one is hotter than the others after a drive when you been experiencing the pulling.
Once those possibilities are eliminated, I would look to the suspension parts as samueljackson suggested. The tight - loose comment sounds like a badly worn or loose suspension part. This can be really dangerous. Although the alignment technician should have checked these joints, he might have missed something a little less common like inner tie rods or loose bolts holding the steering rack to the frame. You may also have a bad steering rack. You could drive the car up on ramps, block it safely, then get under the front end and watch each joint and all of the moving components as someone turns the wheel a little bit to the right and left. The engine does not need to be running to do this. There should be no visible play in any of the joints. Check the strut mounting plates on top of the struts also to make sure they are tight, but not binding.
Some worn joints are easier to see with the car on a ramp, others with the wheel and tire off the ground. Checking the ball joints with a normal load (on a ramp) may reveal a bad joint more easily than if the tire is off the ground and the strut spring is pushing the ball joint tightly apart, possibly concealing play in the joint. With the tire and wheel off the ground, you can have someone try to wiggle the wheel with their hands at 6 and 12 O'Clock and at 3 and 9. If all the joints are tight, but the wheel wiggles, you may have a bad wheel (hub) bearing. If you are not comfortable doing this yourself, take it to a good shop and tell them you are concerned that your steering feels tight and loose as you drive down the road, and you want to have all of your suspension joints checked for wear.