According to their site:
Passengers whose baggage is missing at reclaim must, on the same day and before leaving the arrival hall, have a Property Irregularity Report (PIR) prepared by applying to Station Lost and Found Offices with their
Identity document (identity card, passport).
The Property Irregularity Report is filed on the WorldTracer system which begins searching for the lost baggage. When found the baggage is delivered to the passenger without delay, free of charge. For the first five days the Station Lost & Found Offices are responsible for searching for the lost baggage. For baggage not found within five days the
Identity document and
are obtained and sent to the Baggage Services Management. In the event that detailed investigations carried out by this department are not successful, the lost baggage file will be evaluated for compensation.
According to your data, I assume you did the PIR and one week later you did the Baggage Identification Form and sent to BSM (otherwise you should). State that according to the EU LAWS (since the baggage was lost in transit to EU and should have arrived there; EU LAW applies if you are departing from any airport situated in the EU, or arriving in the EU with an EU carrier or one from Iceland, Norway or Switzerland.) the standard terms are:
If your registered luggage is lost, damaged or delayed, you may be entitled to compensation from the airline, up to about €1,220 Exception - if damage is caused by an inherent defect in the baggage itself.
Hand baggage (including personal items)
The carrier is liable if it was responsible for the damage. Make sure to file your claim within 7 days of receiving your luggage (or 21 days if your luggage was delayed). If you wish to pursue other legal action, you must do so within 2 years of the date your luggage arrives. If you are travelling with expensive items, you might be able - for a fee - to obtain a compensation limit higher than €1,223 by making a special advance declaration to the airline - at the latest when you check in. Though the best thing is really to take out private travel insurance. There is no standard form for the special declaration. It is up to the airlines to choose the type of form they provide.
There is no specified date where one baggage is termed lost. However, I would suggest you submit an air passenger rights EU complaint form to your airline - and make sure you keep a copy for yourself. If this still doesn't work, or you aren't satisfied with the reply, you can complain to the national enforcement body in the EU country where the incident took place. Or, if the incident happened at an airport of departure outside the EU but involved an EU airline, you can send a complaint to the relevant national enforcement body in the EU country you were travelling to. If you want to make pressure, next time you reply to them state you want to be refunded due to the time taken and that you will file a EUCF or higher and place the EU authorities on copy.