as per the details u have given ,
your symptoms are most likely towards ECTOPIC PRGNENCY..
why becoz, if u have got implantation
in the uterus
, it would have shown up in the ultrasound
..but its nott...second thing is pregnency test postive and your HCG
LEVELS ARE INCREASING , WITH SPOTTING ,,,..ITS APERFECT SIGN OF ECTOPIC PRGNNECY..
SO DONT WAIT ..NOW RUSH TO EMERGENCY DEPARTAMENT.. BECOZ, CHANCES OF RUPTURE WILL BE THERE...SO CONSULT ER DEPARTAMENT..IMMEDIATELY..............