Your finger & thumb position look okay there.  But the more likely culprits are not shown in that image.

First potential problem:  it's difficult to see the angle of your wrist.  You want as smooth and natural a curve as possible.  The more your wrist bends the less power & control you can manage.  So you might want to tilt the neck up a bit more in order to make your wrist bend less.  Also, is that a watch?  I typically discourage anything on your wrist that might impede motion, strength or dexterity.

Second problem:  a lot of hand, fringer, wrist, arm pain comes down to using too much pressure.  Beginners often squeeze very hard.  This is a completely natural reaction because playing is difficult at first!  But as you gain more strength, dexterity and control you want to back off on the amount of tension you use to fret notes.  You only need a certain amount of pressure to make the notes sound.  Any more is wasted effort that hinders your playing.

Hope that helps!