Amniotic Fluid Index or AFI is considered to be normal at 8-18.
Medium AFI level is approximately 14 from week 20-35.
After that it keeps reducing and prepare for birth however if its 11.6 its avg please listen to what you are doctor has to say on this and as per as the fetal weight is concerned it is less than normal because in 36 weeks of pregnancy it should be 2.6 kg please have a healthy diet lots of fruits, veggies, milk, curd, cheese, legumes, pulses, sprouts, soybean, peas and beans, chicken, fish, eggs, carrot, sweet potato, nuts, whole grain cereal etc.
Have plenty of water and take rest..
Discuss with the Doctor if he wants to prescribe any supplements for the weight gain of the baby.
Be positive and good luck!