How far along am I?

Alaina • I`m 27, happily married and we have 3 beautiful children!!!
Okay so I had my last period August 8th!!! Supposedly my calendar said i ovulated the 22nd but we didn't have unprotected sex u till the 28th! So how do I know exactly how far along I am? Could I still have gotten pregnant during when my chart said I was ovulation if I didn't have sex till so many days later??? (4th baby)