It seems like a burden has fallen off her. We now see her really (sincerely) laughing and the like more often. And it is a beautiful smile!
ITA with this point!
Though we like to think of monarchies modernising, there is still great expectation on producing heirs and, I feel at least, male heirs. It's not quite the same world as Henry VIII and his determination to produce a male heir, but having cameras in your face 24/7 and all elements of your private life potentially being leaked to the media must be incredibly stressful, even more so when/if there are real, emotional issues a person or couple has to deal with. Celebrities, royal or not, can't be papped after heaving a heavy lunch without rumours of them being pregnant, and often it seems that press stories about female celebrities revolve around them being pregnant. Steph had seven solid years of constant speculation, and perhaps internal pressure too, regarding her carrying and giving birth to the heir. I cannot anticipate how hard that must have been, especially if there were difficulties conceiving, or even if they had decided to settle into married life before becoming parents. To have that constant pressure must be so draining, and I agree with many on this board that a weight does seem to have lifted from both Steph and Gui too.
And yes, Steph's smile is so radiant and joyful, I find myself smiling too just looking at the pictures! She seems to have re-discovered that glow she had at the time of her wedding, and it is wonderful to see!