Desperate for answers.

Hi, I hope to get some kind of answers here today and thank you in advance.
See, My last encounter was in November. In december I took a HPT and it was negative. No period. In January I take a blood test. Negative. No period. I was given some medication to make me come on my period but didn't take them appropriately and I didn't come on. In March I went and saw the gynecologist and he performed a vaginal ultrasound and put the apparatus atop my stomach and saw nothing and gave me Duphaston. My period came...it's still coming three weeks later. I had taken another HPT that showed negative.
I went and saw another gynecologist a week and a half ago and she too did the vaginal ultrasound and saw nothing.
Something's kicking in my stomach. It's distended as if I'm pregnant and hard. Whenever I lay on it I can feel that something's there. Could a vaginal ultrasound miss a baby at this point? It's been five months now....
Please help.