Hi, I Am 4 Weeks Pregnant, I Underwent TVS Scan

Hi, I am 4 weeks pregnant, i underwent TVS scan where Dr told that there is free fluid seen in POD but after 2 days again I went for TVS where no free fluid was seen. What does this mean, is it a safe pregnancy or ectopic pregnancy, also have done HCG test twice within 48 hours which resulted in doubles.