Girls, hello! The situation is that my daughter is 4 months old and we…

Girls, hello! The situation is that my daughter is 4 months old and we were (were ?) GVs. We've been giving her breast milk for two weeks now, but she's not latching on well. She doesn't take it at all. I had to switch to formula because she wasn't eating enough. Her weight gained 400 grams in a month. She became fussy. When I give her formula, she drinks immediately. My milk when I pump is almost water ?. But she goes to the toilet small amount of times normally and big one time a day sometimes and 2 times consistently. I would like to stay breastfeeding, what do you recommend?