I also have a reduced sense of smell. The cribiform plate is up there
in the sinus region, and the sense of smell is tied into it, so sinus
congestion and/or sinus surgery can cause permanent or limited loss of
smell.
 Your on-going congestion along with the surgery are the likely
culprits.
 People who irrigate and reduce the swelling often report that their
sense of smell improves. The FAQ post explains irrigation which can be
done in variable ways: the Grossan hydropulse (around $90), a neti pot
(around 18$), the neilmed rinse bottle (around 12$), a water pik with a
grossan head (around 35$). a bulb syringe (a few $) and various other
bottles sold by allergy suppliers.
 What people put in their irrigation solutions vary: kosher salt at
various concentrations, some also add calcium chloride, either baking
soda or vinegar (if you want it more alkaline or acidic) and xylitol
are all various additives. The basic rinse is salt water at either a
lower or higher concentration: from 1 tsp to a quart to 1 tsp to a cup.
Some people like sea salt more than kosher salt.
 You can search the group.
 Also, nasal steroids, nasal antihistamines (astelin) may help. So may
oral antihistamines and/or decongestants.
 Good luck, it is weird not to have the acute sense of smell I used to
have. It comes in handy sometimes, but not often.
Judy

I've had two surgeries thus far.  With me, gradually diminishing sense
of smell is a sign that my chronic sinusitis is relapsing, and so it's
time to consider yet another surgery.

You should consult another ENT who may detect sinus trouble that your
current ENT missed.

In the meantime, do what I do:  Use irrigation and topical steroid
sprays to keep your nasopharynx as clear as possible.  And go heavy on
the seasoning when you cook.  :-)