5 month old weight

Ashley • Raelynn Jade 👣💕Raven Sue 👣💕 Emberleigh Samantha 👣💕 Remington Athena👣💕

My 5 month old was 5lb 10 oz at birth but 6 weeks early and she is only 9 lbs she throws up every time she eats the doctors are blaming us I’m just not sure what to do