Your post from Tuesday was so positive. Then you let your SIL’s perception drag you down.
You have to remember that as in-tune as your SIL may be to your H’s moods, she isn’t a barometer of his happiness. Everything’s relative. She’s picking up on vibes. Like you said, you’re not the happy couple of the year yet. She’s simply picking up on that vibe and comparing it to the time when you were such an happy couple.
The important thing isn’t to compare your R to “the happy times.” The important thing is you’re on the road to new happy times. Look at how things were – even a month ago – and pat yourself (and your H) on the back for becoming such an happy couple (in comparison to then), and for your continued progress towards marital bilss.