looking for help up wind
It''s an interesting conundrum you have. There''s a good amount of info in your message, but perhaps we need more info to diagnose what''s going on.
How does the rudder feel in a breeze? Do you have a lot of lee helm? Neutral? Weather helm?
You say the centerboard is definitely down. Have you had the boat hauled and verified that the board goes all the way down, to the point that the pennant goes slack? Perhaps the CB is hanging up on something partway down.
You say the boat will not gybe, correct? This is odd. How much of the rudder is in the water? Is the rudder a kick up rudder (does it pivot backwards)? Perhaps the boat is front loaded so much there is not enough rudder in the water. This problem may also go back to the question about the balance of sail forces and rudder forces on your boat (lee helm vs. weather helm). It''s hard to imagine being unable to gybe a boat if the main is first sheeted in to center the boom.
What about the condition of the hull (been cleaned lately?) Dragging a propeller or auxiliary motor in the water?
Maybe your best bet would be to ask a more experienced skipper (like a club racer) to come sailing with you to try and find out why your boat won''t handle well.