question?

if i don’t eat a lot does my baby not put on a lot of fat? i’m 33 weeks and i have gone off food. It doesn’t make me sick or anything i just cant be bothered to eat. I don’t cook meals anymore i just grab snacks. I take pregnacare for pregnancy and aspirin (moderate risk for preeclampsia) when i just hit 32 weeks i got a scan the day i turned 32 weeks and he weighed 3/11oz, they said he is growing normally and perfectly but a lot of women have said their baby was like 4pound or 4 pound something? what does the vitamins do for him? do i eat more meals? i’m not starving myself selfishly i will happily eat to make my son healthy i just don’t want to make him overweight or cause problems for him and myself if i make myself overweight. Any advice would be great please!