How much does what you eat affect the baby when breastfeeding?

Anna

Hi ladies, my baby is really gassy and fussy lately so my husband wants to give our baby sensitive formula instead of my breastmilk. I'm a FTM and my LO is 5 weeks. I want to breastfeed! After struggling a bit, we're getting the hang of the whole breastfeeding business. He's feeding well but I feel so guilty that what I eat has a negative affect on him. I don't want to eat anything because I can't figure out what I'm eating that's making him feel bad. How much does what we eat affect them? Thanks!