Hi thanks for your question. The reason for you abdomen feel heavy is your weight as 5 weeks pregnancy would not cause increase in abdominal girth to the extent that you will feel heavy .Feeling heavy and full could not be symptoms of ovarian cancer. Most probably your HCG (you have mentioned “high” probably a spelling mistake) levels are rising which are do not rise in ovarian cancer but commonly hydatidiform mole a benign condition but if timely intervention not done can change into malignant condition caled as choriocarcinoma.I would suggest you to remain on regular follow up of gynecologist. Asking any question which pertains to your health is not irrational. You can discuss your issue at length with your physician. Hope this answers your question.