Judging from what she shared, I would say lose the night bottle. Children above 12 months need not have a night feed. It sounds like mom is using the night feed more as a way to get bubs to sleep at night and also as "an insurance" to soothe mom's fear that bubs' not eating/drinking enuf.
Few things to emphasise:
1) There is no hard and fast rule for when children can sleep thru night. Some do it as young as during infancy and some will still wake up during the night when they are 5-6 years old. All comes down to child's internal traits and sleep schedule. As long as the child has 10-13 hours of sleep + nap(s) per day and the child seems otherwise happy and active (not easily tire), there is no reason to worry about the child waking up at night. He or she will sleep thru in his/her own time.
2) Mom seems concerned about child's weight/growth... keep emphasising that her child is skinny. Define skinny. Is it skinny compared to other kids? If this is the case, stop comparing. Each child is born with their own genetic propensity inherited from parents or even grandparents/uncles/aunties. If mom is worried re the child's growth, there are a few things she can do to:
- plot the child's weight and length/height: keep monitoring the growth (weight + height) for every 2-3 months and see if the child's growth crosses percentiles (eg: continuously falling or not gaining any weight for a certain period of time). it is important to emphasise that if the child is born small or "light" and continues to track the same percentile (eg: born in the 5th percentile and growing according to the 5th percentile), the child is fine.. he or she is just tracking her own genetic trait.
- get a full blood test done: test for any genetic anomalies as well as for nutrient deficiencies, eg: iron deficiency etc. If it's nutrient def, it is easy enuf to treat, all you need is just to give the child the nutrient supplement for a certain period of time and he or she'll be back on the right track. If it is genetic illnesses (eg: coeliac - which by the way is not common amongst children of asian decent), then at least you'll know that there is a reason for the poor appetite. you'll find that most times, child is doing fine with no deficiencies etc or just a minor def like iron def which is common amongst children with poor appetite and children who rely too much on milk. Again, if it's iron def, it is easy enuf to treat.
Without having the family and child's med history in front of me, I cannot say much. The best advice for any mom who is worried re their child's growth is GET IT CHECKED. Do the growth monitoring and take the blood test. Address thsoe worries and if everything comes back negative, at least the mom can have the peace of mind that the child's normal and it's just a behaviour thingy.
After 12 months, children will go thru a period of poor appetite-good appetite-poor appetite.... that's because during toddlerhood, their growth slows down and they do not need to put on as much weight as when during infancy. It is perfectly common that children will eat or drink less when compared to their infancy time because they are just regulating their appetite according to the physiological requirement of their bodies.
The worst thing a parent can do is to compare their children against the growth and performance of other children. I understand that she has some worries re the development of her child (the talking and walking) and again, there is no hard and fast rule when children achieve those milestones - some faster, some slower- and the developmental age range in the 1st 2 years is pretty subjective.. one of the reason why pediatricians and health professionals hesitate to formally assess the development of children below the age of 2.
So, that is my best advice: GET IT CHECKED.