Hello,
As per your scan there is nothing much to worry. Fetal heart is seen at 7 weeks by a trans-vaginal scan. Yet, the spotting that you have needs to be attended. I advice you to inform your doctor about this and get treated. Meanwhile, take bed rest, avoid intercourse and exertion. Susten is progesterone, a hormone useful in the maintenance of pregnancy. If you have already started using Susten, rule out that the discharge is not due to the dissolved tablet. Good luck.

hello there..
Fetal heart beat is usually seen by 6weeks in transabdominal scan and 5weeks by transvaginal scan. But its not necessary as sometimes The heartbeat may not be detected for reasons that include: tipped uterus, larger abdomen, or inaccurate dating with last menstrual period. Concern typically develops if there is no fetal heart activity in an embryo with a crown-rump length greater than 5mm. As you said your scan shows a yolksac and fetal pole which are good signs and you can still wait for the heart rate to appear. Get an ultrasound repeated after a week in which size of crl can be compared and also heartbeat can be checked. Sometimes dates are miscalculated just how far along you are, which can lead to expectation of heart beat very early.

But one thing which is alerting is you had vaginal bleeding. It can be an indication that your pregnancy might be heading to abortion and can be related to no visualization of fetal heart beat. Still you should wait for a week or two, sometimes bleeding stops and heart beat appears. Susten is a progesterone, there are still studies going on to prove its efficacy in withholding an abortion process. So not all doctors reccomend it but still theres no harm taking.
Also avoid intercourse, heavy work, travelling.Take adequate rest and nutrition and do continue your folic acid tablets .