eating while breastfeeding

Ah
I'm not a big eater. i try to make sure i do 5 small meals a day but with baby crowding my organs i get full really fast and I'm often too busy to eat. my doctor was telling me that i'll have to eat more calories when im breastfeeding and I don't even think I'm enough calories now 😕 I'm 33 weeks and it seems like every week my appetite gets worse. 
did you notice a change in appetite while you were nursing or did you have to force feed yourself? lol I'm so nervous about it.