the baby is small !!!!!!

by this app i am 9 weeks and 3day but i went to the dr yesterday and she check the size of my baby and she said the baby is 8 weeks and 5 days but she said it's normal and she told me are you sure about your first day period day i told her yes .. what can i eat to let my baby getting big. my dr said i should eat fruits , vegetables, proteins  and wholewheat. pls told me some advance. still no prenatle and calcium vitamins only i take folic acid, aspirne and progstron.