I think you're looking for the 'user' option of qstat. qstat -u username lists all jobs belonging to the given user. Wildcards can be included with a backslash: qstat -u \* lists all jobs.
To answer your specific question (total jobs), you can use wc to count the lines that qstat outputs:
qstat -u username | wc -l
But that will give two more than the actual jobs because qstat has two header lines. So the full command you may want is:
expr $(qstat -u username | wc -l) - 2
Which asks for the jobs by user username, counts the numbers of lines, and subtracts 2.