6 weeks and 1 day but no gestational sac

I am 22 yr old, I had my last period on 4th April. And I have missed my period this month. My boyfriend and I had unprotected act but he din't ejaculate inside me. As yet I have tested positive for pregnancy 4 times. I was asked to do a ultrasound sonography. The reports showed no gestational sac and no embryo. Nothing was seen at all. My both the ovaries are normal and in perfect dimension. Even my uterus is normal and in normal dimension. And the doctor prescribed me tablet Primolut thrice a day after food for 3 days and asked for sonography once again next week. I wanted to ask that as my gestational sac and embryo are not visible, is it ectopic pregnancy ? And if ectopic pregnancy it is, can it be aborted ? I want abortion done as I don't want this so early. Can it be normal or are there any chances of complications ?