I agree with the other posts, I would really want to have an US! I am sure everything is fine, but for your own peace of mind and to not spend 4 worried weeks, it would really help! With both my sons, they couldn't hear a heartbeat at 11 weeks. They did an office US with a very old fashioned machine, and could see one with my first son. With my second son, they couldn't see one either, but could see him moving around! I still felt worried, but they had me come back in just 3 days and then we saw one. I would have gone crazy waiting 4 weeks.
Good news about your BP!!
Suzanne (37) and DH Tony (41) + William (9, severe PE, born at 32 weeks) and Freddy (6, fairly typical pregnancy) and Baby (due approx. 8/26/04!)