I am working in foreign country and did not pray Jumu'ah for three months, instead I just pray regular Zuhr. No Muslims live in my city and Friday is a working day. I am afraid that this is Haram and I may stay here for several years without finding the chance to pray Jumu'ah (Friday). Really I am in trouble and I need your advice.

Praise be to Allah, the Lord of the Worlds; and may His blessings and peace be upon our Prophet Muhammad and upon all his Family and Companions.

Before answering your question, we would like you to read Fatwa: 81642, concerning rules of residing in non-Muslim countries.
As for your specific situation if it is as you mentioned, then it is not mandatory for you to do pray Jumu'ah but you must pray Zuhr instead.
To know the maximum distance between where you live and the mosque that makes Jumu'ah obligatory on you, please read Fatwa: 85462, and to know the minimum number that can pray Jumu'ah in congregation please read Fatwa: 84455.
We call your attention to the fact that working on Friday is not an excuse for missing the Jumu'ah prayer. If those in charge of the work compel you to work at the time of Jumu'ah, then you should quit this job and Allah will give you better. Allah Says (interpretation of meaning): {…And whosoever fears Allâh and keeps his duty to Him, He will make a way for him to get out (from every difficulty). And He will provide him from (sources) he never could imagine.} [65: 2-3].
Allah knows best.