Theory:

THE DIFFERENCE BETWEEN CONTINUOUS AND PERFECT

We mentioned that there were two kinds of actions used in English grammar.
The first kind is a short quick action that lasts a few seconds, like kick a ball or break a window.
This kind of action is called a SIMPLE action.

The second kind of action lasts for a longer period of time, like doing homework, or cooking a chicken.
This is a CONTINUOUS action.

How you look at the CONTINUOUS action gives the PERFECT action.

The CONTINUOUS only means that the ACTION LASTED FOR A PERIOD OF TIME, but does not say how long it lasted and does not discuss when the action finished.
This is done with the PERFECT (Which means finished).

The PERFECT gives you THE DURATION OF THE ACTION in several ways, by using FOR and SINCE, but it also gives THE MOMENT WHEN THE ACTION FINISHES, which controls the kind of perfect action you mean.

There are THREE POSSIBILITIES.

THE PAST PERFECT
The CONTINUOUS action can FINISH AT SOME TIME IN THE PAST which gives the PAST PERFECT.
For example:
I had been sleeping for 2 hours when she called.- PAST PERFECT CONTINUOUS - duration 2 hours - moment of termination in THE PAST: when she called.

THE PRESENT PERFECT
The continuous action STARTS IN THE PAST and FINISHES NOW, which gives the PRESENT PERFECT.
For example:
I have been sleeping for 2 hours. - PRESENT PERFECT CONTINUOUS - duration 2 hours - moment of termination: NOW, by definition.

THE FUTURE PERFECT
The continuous action can START IN THE PAST and FINISH AT SOME TIME IN THE FUTURE which gives the FUTURE PERFECT CONTINUOUS.
For example:
It is now 6:00
You started playing tennis at 4:00
At 7:00 you will have been playing tennis for 3 hours. - FUTURE PERFECT CONTINUOUS - duration 3 hours - moment of termination 1 hour in THE FUTURE.

TO SUMMARISE:
PAST PARFECT CONTINUOUS - HAD BEEN PLAYING
PRESENT PERFECT CONTINUOUS - HAVE BEEN PLAYING
FUTURE PERFECT CONTINUOUS - WILL HAVE BEEN PLAYING