It is common for ultrasounds to not detect anything during early pregnancy, especially before the gestational sac becomes visible. At around 5 weeks, it is possible that the embryo is still too small to be detected by ultrasound. Other factors such as incorrect dates or an ectopic pregnancy can also contribute to a lack of visible findings. If you are concerned, it is best to consult your healthcare provider who can provide further guidance and possibly schedule a follow-up ultrasound in a few weeks when more accurate results can be obtained.