Hey, there!  These are good questions.  

First, does it feel natural & comfortable to you?  Can you play the chords smoothly & change between them?  If so, then you doing fine.  The C major chord looks good, but it looks like you thumb might be awkward on the D major chord.  You might find it more effective to move your thumb a little more to the bass side of the neck to oppose the pressure of your fingers on the treble side.

If you haven't yet, I encourage you to work through the Guitar Fundamentals course.  In particular this tutorial covers basic open chords with the proper mechanics.  This lesson is the D major chord & the next is the C major chord.

https://www.guitartricks.com/lesson/31266

And I cover general fretting hand mechanics here.

https://www.guitartricks.com/lesson/10654

In lesson 2 in particular I discuss what I call the axis of power that is effectively keeping opposing pressure between your fretting fingers & thumb.

Hope that helps!