You’re holding the bass too close to your body on the left side. You can’t hug the bass. The bass body should contact right side of your abdomen alone, with the bass neck angled out and away from your left shoulder. This will free your arm up, and you won’t get all tied up on those upper frets…
I know what I’m talking about, because I was there too…
In this pic I am holding the bass further right, but it’s really the same mistake; neck is too close to my body.