maybe ur fetus still small and wait another weeks to go.. Some of my friends mommy chance their OB and waited for a couple more weeks to see the progress. after 10-12 weeks they saw they little one growing, some don't only empty sac. Dont worried to much, think positive. But u having a pain strike on ur stomach go to OB asap maybe ectopic.
If u got ectopic , i got something to tell. I have been through that situation but in different way. I didn't know i'm having another baby at my right Fallopian tube until i was miscarry the other one in my sac. I'm having still a symptom of pregnancy while i already miscarry for 3 day (9 weeks preg) i'm see my doc to do some cleaning my sac and tell about my worried either i'm still preggie or just my paranoid feeling. then i was shock my hcg level high, i got ectopic without any symptom of pain. and do the internal ultrasound cant detected which Fallopian my fetus go. i been do repeated the internal ultrasound and found internal bleeds from my right tube (after a 4 days checking).. So i lost my tube, but it least i got another one on my left side. Any thankful, i'm safe even i got terrible bleeds on internally my fallopian rupture already. I got the right choice and think the positive way.
try for another choice, i heard if earlier u can eat some medicine if u got ectopic.