Distilling problem

[dawannabe]

I just ran my reflux still for the first time and the temp sat on about 79-80 degrees for a couple of hours and i collected about 1.2 litres of spirits, but then the temperature started fluctuating and went up to 88degrees within the next 20 minutes which is when i stopped collecting the spirit. I ended up with 1500mL at 90% but i thought i would have nearly double that amount?

Was my wash not so good?
or is there something wrong with my still and how i am using it?
Help would be greatly appreciated