Lot's of variables. I've done a few runs with PK and average 2-3 zips per plant with a 5 to 6 week veg time. I'm in soil using a 600 watt. Show a pic it would help.
Then I wouldn't be worried about yield yet. Do some reading and keep your plants nice and healthy and you then will be rewarded with a nice harvest. PK is a great strain with nice rock hard nugs. Good Luck!