It is very unfortunate that you are facing such a situation. Sometimes, fetal cardiac activity may not be visualized properly in early weeks due to poor resolution and it also depends on the expertise of the sonologist. A repeat sonogram along with serial titres of serum beta-hCG
gives an accurate status of the pregnancy
. Doubling titres every 2-3 days indicate favorable progress. Please discuss with your consultant on these lines and do not lose hope. Wish you good luck.