Is my baby boy going to be ok??

Ok so I have been absolutely terrible at taking my vitamins due to them making me sick. I have been eating like my doctor told me to since I’m having a hard time gaining weight. I also am starting to drink Ensure to get vitamins that way. Will my baby be ok since I’m not taking vitamins? The only thing we have been told is that baby is measuring small but that it is due to the fact that I am 5’0” and weigh 90 pounds. I just want my baby boy to be ok!!