please help

When baby was a week old, the most scary thing happened to me. Baby had pulled up blanket to face while asleep. Not sure how long he had it covering his face. Saw it until I woke up for the day.

Thankfully everything was ok. Since then I no longer let him sleep with blankets.

Now I’m very anxious and depressed thinking of that event may have cause any brain damage if he lacked oxgygen.

What are some signs That would show any damage done that i should be looking out for

please give advice to this stressed out mom

baby is 5 months and has reached all milestones