Sometimes let down can take a little while, maybe massage your breasts or breast depending on what side you are about to feed on a little while before she is ready to feed. also once she is attached does she feed well cus I was thinking maybe once you have let down it might be too fast? With my DS3 i found I had this problem so once he was attached and we were both comfortable I would lean back in the chair so the milk had to go upwards kwim??