Week 8 based on last menstrual period but ultrasound showed 5.5 weeks

Not to worry too much about it first. Counting based on last menstrual period is just an estimate. The ultrasound scans are most accurate because it takes the crown rump length of the embryo to give an accurate measurement of your embryo. The doctors and us won’t be able to know when we exactly ovulate or when the fertilised egg implants onto your uterus. Wait till your next scan then see how. Have you made an appt with a gynae. Let them know about your spotting, they make give you some meds to stabilize the pregnancy.