How much weight should i lose?

iam 26 year old mom of a 1.5 year girl. my height is 5.4" and weight 58 kgs or 128 pounds. is this right for my height? iam average build now, but i used to be quiet slim before my baby (52 kgs or 114 pounds). i want to get back to that weight and be slim again but everyone including my husband is against it( not very much against though). they say iam ok now and if i lose weight i will look thin. what do u think