Mine is the same. She’s a little over 7 weeks old and really only smiles when waking up from a nap or having gas. I can’t wait until she smiles for real and starts laughing!
Totally normal and every baby is different... my girl will laugh in her sleep or smile sometimes when she's dozing and i kiss her but otherwise not really smiling yet
Mines been smiling since birth he's now 6 weeks old but my friends 6 month old barely smiled till 5 months. They all progress on their own timeline so don't worry