hi my doctor told me that i was 8 weeks pregnant when i went for a scan the baby was no were to be seen so i had to go back the next week and what it was with me i was only 5weeks so that was why they could not see the baby hope that helped
You may not be as far along as they think. Or it could be a tubal.
at 7 weeks the baby might be just a bit to small to be seen on a scan which is why normally a first scan is taken at 12 weeks pregnant. Have they asked you to go in for another scan in a few days/weeks? i wouldn't worry about not seeing the baby at the moment as long as your HCG levels keep rising and your still getting a BFP i don't think you have anything to worry about. Congratulations :)