You need to have a regular period, every month on time, to maximize your chance of getting pregnant, having irregular period, or absent period can mean you're not ovulating. A one day bleed may not have been a period
, it may just be breakthrough bleeding
. You should have sex every other day throughout cycle days 10-22 to really maximize your chance of getting pregnant, it's all about timing, and it has to be perfect, so relax, it will happen!