Audrey, personally I always think engaging a relative, esp if it's an IL, will be difficult to manage since you cannot make demands. Even if you pay her, she is still an elder in the family, so you can't really complain if something is not done to your preference or expectation. Really must consider carefully whether you can get along with this person for 1 full month cos unlike a CL, you cannot terminate her without repercussions. Somemore, you don't speak her dialect and different dialect groups have their own practices, so it's really not advisable. BTW, are you able to get your own relatives or mum to go over to JB to help you for 1 month?
Re baby's weight, don't worry too much about the difference, cos it's all estimated. So long as baby is developing well, it's all fine.