hi
the waiting is difficult, i am so sorry.
i did ivf with both my successful pregnancies and at the clinics, they will not do an ultrasound before 6weeks (and even then, reluctantly), because of the difficulty of locating a heartbeat. prior to six weeks, all that seems evident is the fetal pole.
the waiting is agony, but in this circumstance, medicine is on your side...dr's do not expect to see a h/b at 5 weeks.
vaginal u/s is much more telling at this stage of the game. where the embryo implanted can also have a great deal to do with located the h/b on an abdominal scan.
good luck, kitten.