I am really sorry about this. With a good sonographer using a good ultrasound machine, you would be able to see a fetal heart at 7 weeks. If I were to make a plan i would have waited, only if the measurement equal 6 weeks or less as it would be hard to appreciate a heart beat. In you case with the measurements are close to 8 weeks, so it does not appear promising. I am sorry to say this. I would suggest a surgical / medical management for a miscarriage. As this is a mentally traumatising time for you, you should make the decision which you would not regret over a long period of time and you should be beyond doubt as its your baby.