Well, allergic rhinitis does indeed cause a blocked nose, with itching, running and sneezing. However if you still have a blocked nose after treatment and it is unilateral (one sided) then one must suspect another problem.
Now, if you have noticed an asymmetry of your nose on photographed and blockage of one side of the nose, then a deviated nasal septum does seem likely. One must remember that there are other causes of unilateral nasal obstruction e.g nasal polyps and the definitive diagnosis needs to be made by an E.N.T surgeon.
If a deviated nasal septum is diagnosed than a functional operation called a Septoplatsy will cure your obstruction, but this is only functional and will not affect the outside appearance.
Pick your surgeon carefully and at the same time as correcting your septum, he could straighten your nose (Septorhinoplasty)
Good luck