If you try to repair too many problems at once, you'll just get more frustrated.
Stamina is not a Problem
Come up with concrete steps to take. Example: If stamina
is a problem, set up a full-length proctored test experience for yourself.
If you have trouble with a particular question type, set aside a couple
of hours to work on nothing but that question type.
Set up a similar schedule for each week of practice
time.
Each week in the time that remains, continue this
process, and try to make some progress on a limited number of your
problem areas.
Don't seek to solve every problem, because seeking
full solutions may be setting yourself up for disappointment. But setting
particular goals will yield significant results.