Worried if baby is eating enough.

I had my baby boy the 16th got disharged the 19th then we got readmitted again the 20th and got released again yesterday. My baby boy wasnt eating enough and was dehydrated also had slight jaundice that made him lethargic. He was doing so good in the hospital eating. But now that we are home again im scared hes not eating enough, and will be dehydrated again. I am breastfeeding. How can i tell if he is getting enough every feeding?