Living overseas and concerned that you haven't filed US taxes? If you are an US expat, you should consider getting into tax compliance as;

Filing US taxes is required even when working and earning an income overseas.
Owing US taxes could cause problems for your passport renewal.
The unpredictability of the US Government lately, particularly in the realm of immigration, adds to the unknowns.

On a positive note;

You are very likely not going to owe US taxes as the Foreign Earned Income Exclusion and the Foreign Tax Credit, used in combination can reduce most taxable income.
But if you are self-employed or living in a country not covered by the Totalization Agreement, you could owe the taxes that fund your Social Security.
There's certainly no rule-of-thumb on how many returns to file. But most people who file the last six years satisfy the IRS system. However, some people try to file less than that (three, four or five) and see how the IRS responds.
Filing 2020 2021 returns will provide $3200 in pandemic stimulus payments to you even if you lived abroad (if you meet the criteria).

Find out more about expat tax preparation and other expat tax issues here.