Small amount of vomiting even after burping is usually there - nothing to worry - it's called regurgitation.
You have to check the baby weight regularly - if weight is ok - gaining on week to week basis - then normal.
If child is not gaining weight - consult your child specialist.
Next Steps
proper burping is the best way to decrease the vomiting after feed - it removes the air ingested while breast feeding.
Health Tips
to check for any medical reasons - you have to visit your child specialist.