Had to quit breastfeeding 😔

On Saturday I had to stop breastfeeding my daughter due to my milk supply becoming too watery and her not being able to have it settle in her stomach.  She had frozen breast milk Friday morning at my parents and got sick. (They didn't think anything of it). Then breastfed Friday evening I breast fed her and she got sick and I just thought she ate too much. Then Saturday morning she breastfed again and threw up twice.... one was probably 2-3 oz worth. When I pump  my milk is so watery. I found out it's due to my diet and not being able to consume enough calories. Due to my job bring so busy it's hard. So I've switched her to formula and she has done just fine. I'm sad though because I feel like I'm doing wrong. I try to eat more but it's so hard and I don't want her keep getting sick. I just feel bad. 😔 anyone else ever have a hard time when they stopped breastfeeding?