Day one is the first day of your period.
So on average you have 37 days between the first day of one period and the first day of the next.
Ovualtion occurs around 14 days before your period (it is those hormones that cause the period), so you are looking at ovulating about day 23.
Sperm can survive for upto 5 days, and an egg is viable for upto 36 hours after release from the ovary.
So from day 18 to 24/25 is your fertile window going by the details you have provided.
Around this time you are likely to notice the discharge/mucus from your vagina is kinda like egg white - fertile mucus.
(occassionally some people have kooky cycles and ovulate at random times but that is not the standard.)
i'm assuming bd means you had sex? But it would seem this did not occur in your fertile window.