Good for you for sharing, for having a heappy, well-adjusted baby, and for your wife for wending the enormous transition to full-time mommying. Becoming a parent can trigger so much stuff, from the past and not, that even the easiest, smoothest baby doesn't guarantee overwhelming emotions won't come into play. And in fact even without anything emotional getting called up, it's just a huge upheaval, as you seem to understand. It's great you balance so much of the work, but getting to be out of the house regularly, focused on a You pursuit (career) does change things and give you something your wife doesn't have right now.
I would urge you to be empathic and validating--asking open-ended interested questions to learn what this experience is going like for your wife; enable outside, non-baby time for your wife as it is possible (what and whom did she used to enjoy spending time on? which new pursuits might be of interest now?) and also keep bringing up recheduling that appointment with a counselor because what new mom couldn't use that?
Mostly remember that this transitional time goes fast, even if it doesn't feel like it, and try not to feel alone because you aren't.
Best of luck to you both.