@J0ey 
I discard the domain discussion first.

CISSP is a CAT exam with 100-150 questions.
Discard the CAT element first, I use simple math.
Using 150 question as a baseline, this means on average you need 1.2 minute to answer each question. When you say you are running out of time at 120 question (you have used up your time but not being kick out for other reasons), this means you are using 1.5 minute to answer 1 question which already exceed  (you spend 25% more time on average) the allowed time (unless you use 1.5 minute and answer all the 100-120 question correctly, then you are likely able to pass)

The basic question you need to ask yourself is

• why you are taking this long to complete 1 question,
• what take you so long? 
• What's your weakness?
• Are you spending too much time in reading / understanding the question or you understand the question but you are spending too much time in choosing the right answer?

Some people want to claim, they finish with 100 question , some finish within 110, some may finish 150 question and got a pass. I like ISC2 exam where you are not given the exact score and in this way I don't need to compare or completing with other on who is scoring higher mark. Regardless 100%, 80%, a pass is a pass to me.

But to the people who did not pass the CISSP, the number of question you attempted reveal something. Just my interpretation, I could be wrong.
1) if you are being kicked out of the exam within 100-120, and saying you have failed, this mean you really need to brush up, because the system foresee you are unable to pass the exam even you answer the rest correctly ( ie too many wrongs).
2) if you able to finish 150 question but failed, then looking at the testing result and the domain proficiency make sense and work harder on those domain below Proficiency.

You case is neither 1 and 2.

I can only say

• either you spending too much time on reading the question in general or;and 
• you are not familiar with the topic/domain ( even for the correct ones - domains with above proficiency because you can be too unsure what is the right answer and spend too much time but you got the right answer eventually)  or;and

you may need to improve time management on the question.

And there is simply not enough "data" to see which domain you are under Proficiency because if you speed up, your "Above Proficiency" domains could become near/below Proficiency because you have less time to answer.

Good luck.