If i'm 7 weeks and 3 days when did i most likely conceive. my first day of my last menstrual was march 18th but it only lasted about 2days (not normal?

If you're 7 weeks &: 3 days along based on your last menstrual period, then you conceived the week of March 26. However, if your last period was actually in February, then you may have conceived the week of February 26. Try to see your OB soon. S/he can do an ultrasound and give you a better idea of how far along you are. Best wishes. Dr. Anne