I may never get to actually meet my baby

At my 18 week ultrasound, my husband and I found out we are having a little princess. She was measuring great and her heart rate was 161 beats per minute. We tried and tried to get pregnant for one year. 3 days before my birthday inJanuary, I finally got a positive pregnancy test
My baby tested that she may be at risk for Spina Bifida, on my quad results. So, to actually confirm she has it or not, I had to set up an appointment with a specialist to get a more in depth ultrasound of her little spine. 
The appointment rolls around for her spine, at 21w4d. My husband and I were so excited we get to see her again. Everything during that ultrasound was going great. My little girl had a strong heart beat of 165 beats per minute. Until reality hit. The ultrasound tech got up after taking all of the measurements, and went to get 2 doctors in Maternal Fetal Medicine ( high risk doctors). 
The doctors came in, with no sympathy, tell my husband and I that our little girl is measuring small 2 weeks behind at 19w, when she should be measuring 21w. Her weight was 250 grams (8 ounces), when she should weigh about 12 ounces by now. My world shattered. Then, we got more devastating news. My placenta is not working properly. She's small because the placenta is not giving her enough nutrients. Also, the cord has reverse blood flow. Instead of blood pushing out, the blood is holding back in. Not only that, our little girl has echogenic bowel, and low amniotic fluid.
The doctor was sympathetic at all. He told my husband and I that there is a possibility that this won't end well (as in, lose our baby).  
He told me to come back and check her growth in 2 weeks. If she hasn't made any progress by then,  then I have to take medication to mature her lungs. If that doesn't work, I will have to deliver her early, and we all know what that means. My doctor told me if he had to guess, I'll have to deliver her within the next 3-4 weeks. Only leaving me at 23-24 weeks pregnant, not viable to life. 
I never in a million years thought this would happen to me, after trying for so long, for it all to be shattered in a matter of weeks or days...