Explain..

So my boyfriend thinks baby is not his all because I'm 8 months pregnant. We started dating April 5th, found out I was pregnant around June 4th. Docs told me I'm due January 29th. He's thinking there's not 10 months in pregnant but yet I'm already 8mo pregnant and have about 9 weeks left ... he just saying I would have gotten pregnant. Before him..& that's not possible. Id be further along. Does this make sense ugh I'm trying to explain best I can but it's kinda hard