Fertilization occures during mid cycle of period after ovulation . In general rule we calculate pregnancy week from Last menstrual period. So by dates you are 4 wks
pregnant and according to date of fertilization you are 2 wks pregnant
Next Steps
wait and watch . consult gynecologist if taking treatment for infertility.
repeat BHCg after 48 hrs . doubling of Bhcg level is suggesting good pregnancy.
trans vaginal ultrasound at 5 wks .
Health Tips
consult to obstetrician for detail discussion .