Negative blood/urine pregnancy test and confirmed pregnancy via ultrasound at 15 weeks?

Im sorry to hear about your situation. My sister is 20 and going through the SAME THING. On top of the belly weight gain, shes been sick (naseous and puking for over MONTH now) and has missed TWO periods which, she NEVER skips. Shes been eating stuff shes never liked before, sleeps all the time and swears she feels something "moving" inside her belly. Every test has been a big NEG. She too isnt convincing herself shes preg, she blames it on everything else but pregnancy... which who could blame her, after so many negatives, shes conviced shes not... BUT im not. She to has seen a few docs and they all say no... but then they say NOTHING is wrong with her. Well im sorry but people just dont wake up sick one day and have it last for months and gain weight and feel stuff moving in them if something isnt wrong!!!! She did tell me that our aunt told her that home tests havent worked for alot of females on that side of the family due to low hcg levels... and most had to do the blood tests. Honestly-- i say go with your instincts. YOU know your body better then anybody does... and obviously you know what being preg is like and what to expect. I'd def say careful what meds you take, take vitamins ect atleast until you know FOR SURE. thats what i told my sister as well. Better safe then sorry! I hope you get back answers.... i know it drives me CRAZY watching my sister go through it, i cant imagine actually being in that postion!!! Good luck to you :)