Breathe. 
I have no idea why your doctor would suggest that unless you have some actual risk factors. As far as I'm aware, the ultrasound to check for down's syndrome is usually only done on women over 35.
I'm not really a worrier, so I'm afraid I can't help much with that. All I can say is that the odds are very good that your baby is perfectly fine.
Please don't let your fear keep you from a homebirth. I let my husband's fear keep me from one with my oldest son. I went to the hospital because of fear and I wound up with an unnecessary cesarean, which resulted in a year of pain. My other 2 babies were born at home, unassisted. I had moments/weeks during my pregnancy with ds2 where I was completely terrified, certain that the dr who cut me had been right. I knew what he said was completely illogical, though, so I ignored the fear because it wasn't based in reality.
There's a good saying that might help you..."Do it afraid". You don't have to get rid of the fear to do something, you just have to not let it control you. Try not to let the fear/worry influence your decisions.
I have no idea why your doctor would suggest that unless you have some actual risk factors. As far as I'm aware, the ultrasound to check for down's syndrome is usually only done on women over 35.
I'm not really a worrier, so I'm afraid I can't help much with that. All I can say is that the odds are very good that your baby is perfectly fine.
Please don't let your fear keep you from a homebirth. I let my husband's fear keep me from one with my oldest son. I went to the hospital because of fear and I wound up with an unnecessary cesarean, which resulted in a year of pain. My other 2 babies were born at home, unassisted. I had moments/weeks during my pregnancy with ds2 where I was completely terrified, certain that the dr who cut me had been right. I knew what he said was completely illogical, though, so I ignored the fear because it wasn't based in reality.
There's a good saying that might help you..."Do it afraid". You don't have to get rid of the fear to do something, you just have to not let it control you. Try not to let the fear/worry influence your decisions.