Weeks, your ingredients are right on the mark for basic divinity. I would first inquire of your weather when you were making this. Was the humidity above say 60%?
Secondly, I don't think you're cooking your syrup nearly hot enough.
Divinity, I always go to 252 degrees (F).
Mazetta (marshmallow creme) at 242
Tender/cut marshmallows at 238
Here's how I make mine...the arm-saving way:
I cook my syrup to 252 degrees (F) and remove it from the heat and allow the boiling to subside. Meanwhile, I beat the egg whites in my stand mixer until they are stiff, but not dry.
With the mixer on high speed, I very slowly and gradually pour the hot syrup into the egg whites -- and once you begin to pour, don't stop and do not scrape the bowl!! I continue beating, after all the syrup is incorporated, until the mixture just begins to lose its gloss and holds its shape when scooped up with a teaspoon. Depending upon altitude and humidity, it should take about 10 to 12 minutes to reach this point and it will be very fluffy. I then add the vanilla into the mixer and blend well. Any nuts that are added, I fold in by hand.
Then, working as close to lightening speed as I can manage, I drop the divinity, using two spoons, onto waxed paper, or pour into a buttered 8-inch pan and spread the stuff evenly.
I hope this helps, weeks! And GOOD FOR YOU for kicking into candy gear!!!! I'm very proud of you!!