Annie is right. There is no way to tell when the days are that close. Sperm can live for several days inside your body( up to 5) when you are ovulating. So you will not know until the baby is born and a dna test can be done.
When the possibilities are only three or four days apart, there is no way to know until you do a DNA test. I'm sorry, but even the doctor telling you what she did is not all that helpful. Even with an ultrasound, they can't pin it down to a specific day. (Possibly a specific week, but not a specific day.)