Is there a word for people who directly report to me in office?
There are about 10-12 co-workers who directly report to me in office. It's a private company but of very large size.
They are Junior to me in terms of experience and also are below me in Organisation hierarchy. Also I am their manager/boss who is responsible for their annual appraisals in company.
I need to refer those people in many meetings and emails. I generally tend to use word "subordinate" to refer them, but I am not sure if that is the right word to use.
I am not sure "reportee" is valid English word.
Is there a word to for people who directly reports to me in office?
Report is the common word used in this context.
See the 4th definition under noun, in OLD:
Report
An employee who reports to another employee.
Although they are your subordinates by your own description, the word subordinate carries with it the very clear sense that these people are lower in the company hierarchy than you. It would usually be used if there was a need to put emphasis on that detail. For example: "You need to get your subordinates to start doing their job!".
However, if you simply want a word to refer to people that you manage (directly or indirectly), the word report is the usual choice.
If the individual(s) report to you directly you could further qualify the relationship, by using the phrase:
Direct report(s) (Cambridge)
An employee whose position at work is directly below that of another person, and who is managed by that person:
She has a dozen direct reports, but manages many more people.
If one of your direct reports manages four people, those four individuals are your reports but not your direct reports.
I would use "my staff" to refer to all the people reporting to me in the organisation hierarchy.
See the OED definition (22):
a. gen. A body of persons employed, under the direction of a manager or chief, in the work of an establishment or the execution of some undertaking (e.g. a newspaper, hospital, government survey, school, etc.).
and
c spec. in a business organization: (a) the employees responsible for providing advisory and ancillary services to line managers and their subordinates;