IRS Section 121 - Military/FS/Intel Exclusion

[Jon Smith]

Hi. Having a hard time figuring out if this applies to me.  Any info is appreciated.  

My scenario:

2003-2007: FS member; purchase and live in house

2007-2009: FS member assigned overseas - rent house

2009-2021: Non-qualifying USG service - house still rental

Do I qualify for any capital gain exclusion if I sell the property now (2021)?  The section describes a 10 year window - but I don’t understand what needs to take place during that time. Since last FS employment was 12 years ago, am I out of luck or could I get partial credit if it stops being an investment property?

Thanks.