At 6 months and 20 days, it is completely normal that your daughter cannot sit without support. Most babies naturally achieve this milestone between 6 and 9 months of age. No medicines or supplements will make a baby sit earlier. Instead, encourage her development through daily tummy time and practicing sitting with your support or pillows. Ensure she is receiving her routine Vitamin D drops as recommended by her pediatrician. If she cannot sit even with support, has poor head control, or cannot roll over, please consult her pediatrician for a developmental checkup. Otherwise, she just needs a little more time.