Why didn't the doctor see anything when she performed vaginal ultrasound while in fact i was pregnant?

Why didn't the doctor see anything when she performed vaginal ultrasound while in fact i was pregnant?
2 possible answers- either you are very early pregnant- or you have miscarried and there are still pregnancy hormones in the blood stream and urine.
it could have been that your unborn baby is too small yet to be seen by ultrasound. maybe it is still early to have an ultrasound. other chances are that she wasn't checking in the right places, just be patient. Good Luck!!
How far along are you?? The baby could be too small to see yet. -OR- Was your bladder full?? Those are 2 things that would make it hard to see the baby, or even the shape of your uterus.
The most common problem could be that your pregnancy hormone (Bhcg) must be <1000 wherein its difficult to see the early Gestational sac. The other reason, quite rare, could be that u have an extrauterine(ectopic) pregnancy where its not in the uterine cavity but maybe in the fallopian tube, hence, you must have a serial bhcg blood study done after 3 days and also have the vaginal ultrasound repeated after a week to seen the growth,etc.
Your baby was either too small or they didn't look at your uterus.