Thanks for your query.
When the fetal heartbeat fails to show by a certain size of the fetus, it is called a missed abortion
at 7 weeks and 4 days, the cardiac activity of the fetus should have been visualized.
If not, then it is a missed abortion, and you have correctly been recommended for termination of pregnancy
Just to reassure yourself, take a second opinion
Make sure the ultrasound
done is transvaginal on an empty bladder.
If the picture is still the same, please go for termination of pregnancy.
There could be various causes for this.
Make sure that the products of conception are sent for detailed analysis.