Hi!
If you were my patient, I would advise you that is it pretty unlikely that the other gentleman is the father. There is some controversy about whether there is sperm in the pre-ejaculate fluid or not, so there might be no worry at all. If you are 30 4/7 weeks, your conception date should have been right around the 4th of July--which also matches with the dates the doctor told you in August.
I think you are in the clear. It never hurts to do a DNA test though.
Good luck!
Dr B
Wait would it match even if my period was june 8th?
Thank you so much, i believe you! (: