dude, i also struggle with gifting people who are already doing well! my tip is to think about experiences instead of things, you know - a weekend at a nice bed and breakfast, a class for something she's always wanted to try like cooking or crafts, or even dinner at a fancy restaurant she's dying to go to!
if you'd rather get something physical, think about really personal stuff like an old photo album nicely formatted, a decoration item that's actually unique (like from a small artisan shop) or even a good book/audiobook if she's into reading!
the secret is putting creativity into the gift, not money!