I think a good idea is to go to this link:
http://www.allaboutmoms.com/ovulationcalculator.htm
This might be of some help to you. Please keep it mind it is only an estimation of the days and dates. If you are still worried go to doctor, actually did you not report this rape? If so why not this man does deserve to suffer from his actions. If you need to talk I am a rape survivor as well I am here if you need, you can email me at:
alexis_wynter10@hotmail.com
Alexis