we had weight gain issues from birth to seven weeks. she was doing fine satisfied after feedings now she is constantly hungry! sometimes she wants to nurse then starts crying and then spits up everything she just ate. most of the time she is hungry and i am feeding on demand but concerned it might be a supply issue again. how can i tell if it is agrowth spurt she is 9wks now. she has good output and has been sleeping alot. my nipples are really sore because of the increase is that normal after 9wks of ebf for them to be sore now?