I am pregnant. I went to the doctor and based of my LMP I am due June 14,2013. We did an ultrasound and it says I am due June 22, 2013. If you estimate when I conceived from the June 22 it is a few days before my missed period. Is this possible? Would I miss my period if I conceived a few days before my period? Or could my baby be just a week smaller than it should be I am not very big and the dad is not that tall either could that be way my baby is estimating at a week behind?

Calculating conception and due dates is an inexact science. It can usually go 2 weeks either way. I wouldn't be concerned about it

One of my nephews was a small baby inside the womb and now he has a lot of health problems and is constantly getting tests done to see why he is not growing. I am concerned that is might be my problem as well.

One of my nephews was a small baby inside the womb and now he has a lot of health problems and is constantly getting tests done to see why he is not growing. I am concerned that is might be my problem as well.

Then tell that to your OB/Gyn and ask that your pregnancy be closely monitored. Make sure your take your pre-natal vitamins and follow your doctor's advice on diet.

You can ovulate right before a period.

And yes, you sometimes have a period when pregnant, esp first one, or it is light.

So there is no way to be for sure of a exact conception date.
The development of the fetus needs to be watched over the following months, since it is still very small over all at this point anyway