Not enough calories

I’m 18 weeks and have been tracking my calories because I’m overweight and trying to have a healthy pregnancy. Well from the start I’ve been losing/maintaining my weight. I never go above 156 and never go under 150. But ever since I started counting my calories I’ve noticed I’m physically not able to eat more than 1300 calories. No matter how many small meals or big meals I eat, I feel like I just ate at a buffet by the time I hit 1300 and anything over will just make me feel sick. So of course I’m worried about my baby. Will this affect him in anyway? If I keep losing weight am I risking his life? I will be talking to my midwife about my concerns but just trying to ease my worries in the meantime. Picture of my baby bump. TIA