What Could Cause No Sac On A Transvaginal Ultrasound, No Signs Of Ectopic, And An Ovarian Cyst With Mild Right-sided Pain At 6 Weeks Pregnancy?

Hi Drs.i have been tested pregnancy positive with beta hcg 1500 after 6 weeks of last period (16th july) however still can t see a sac from verginal ultrasounds also Dr can t a find sign of ectopic. But it s has found 4.65cm cyst in my right overy. Also I have light pain in lower abdominal right side. What could be the case. Pls assist