Am I crazy?

Hello. I'm needing opinions. I found out on 4/17 that I was pregnant. I took 2 tests that day but got very faint lines but they were there. So I waited until yesterday & took another & the line was very dark. I took a digital this morning & it came back pregnant. My last period was March 21. I was with my boyfriend on April 6-11 which my <a href="">period app</a> says were my fertile days & ovulation days. Sooo I find out on 4/17 which was 11 days from the date we first had sex. So he keeps throwing up 11 days & there is no way it could be his etc. This will be my 3rd child & I knew before testing with my 2nd that I was pregnant just based off how I was feeling. He is making me think I am crazy. I havent been with anyone besides him. I've read about people finding out at 13 dpo and some 12. But I cant convince him that it's possible. Even his family is saying there is no way. So I am just feeling defeated. Is 11 days after being fertile & ovulation normal? My period technically should start tomorrow so I tested 6 days before missing it and got positives.