Please help I'm worried my baby won't grow right

When I was 5 weeks pregnant I got hit with really bad nausea and I couldn't eat without throwing up for about 1 1/2 weeks. I went to the hospital because I had light bleeding they said it was a subchorionic hemorrhage and they gave me two bags of fluid because I was extremely dehydrated. After I got the fluids I was able to eat and drink without throwing up but I still had a lot of nausea. I have been taking prenatal vitamins my entire pregnancy and I have been tracking my calorie intake and my nutrient intake with a fitness app I have and I have been able to get about 500 calories a day and I get all the vitamins I need without throwing up. I'm worried that 500 calories isn't enough and my baby won't grow right or will have birth defects.  I'm now 9 weeks and I have lost about 20 pounds since I got pregnant. I'm not sure if this matters but I was overweight before I got pregnant and now I'm down to a "healthy weight". Could my baby survive on 500 calories if I get all the vitamins I need?