So, I'm fairly new to knitting, but I seem to be doing fine for the most part. I'm starting probably my hardest project so far and I'm having a hard time getting the gauge right. I bought this yarn its gauge says that 17 stitches equals 4 in, and 21 rows equals 4 inches. I need it to be 16 stitches by 20 rows to equal 4x4. I've tried different sized needles and I just can't seem to do it right. Should I go to bigger needles or smaller needles? Please help!!
Here's the link for the hat I want to knit: