Already had catscan nothing showed but my left nostril is really congested and is always blocked why isnt the other nostril like that?

Nasal congestion : You might have a deviated septum that wasn't commented on in the report, which could block the passage or you might have an enlarged/ congested inferior turbinate. These are the common structures that could cause you problems. See an ENT to discuss this.

Blocked nose: There are several causes of nasal obstruction including congestion from allergies and anatomical issues, too. The only way to tell the cause is to have your nose evaluated by a board certified otolaryngologist,