Just saw this post...getting to it late, sorry.
But...I feel your pain. I had a 2-1/2 acre pond completed in July, 2016, and it did not fill due to drought until Fall of 2018. Harrumph. It was about 1/2 full in June, 2017, but it took another 15'ish months to totally fill.
It was simply a lack of rain/drought. When we did get some rain in that dry period the ground would soak up the moisture so fast that nothing was left for runoff to fill the pond. But...the good news is that when the rains finally came it filled up just fine.
I suspect yours will too.
