Why is my nasal always congested but i can't produce mucus?

Swollen sinus ostia: The connection from your sinus cavities to your nasal cavity (ostia) are probably swollen. There a number of causes of this problem. Nasal steroids may help if you have not already tried this remedy.

Vascular: You likely have swelling of the nasal passages, from vascular congestion, which is often due to allergies. Sometimes these are helped temporarily by antihistamines (like zyrtec) or decongestants (like sudafed). Consider seeing your dr or an allergist to see if a nasal steroid, cromolyn or singulair (montelukast) may help your situation.