Ninja pants

I found another fabric store and among other things, got some discounted active wear fabric. I wanted to make either pegs for pirates or the Ninja pants from 5 out of 4. There are lots of guides but still - figured ninjas had less negative ease.
Well..  meh. They slide down and are slightly see through.

So apparently I need a full seat adjustment. And bigger thighs and smaller waistband. I'm wondering if I could add a gusset up the side or if I have to throw away.