I'm about 90lb-95lbs too, short (5'2 - 5'3), partially lactose intolerant, 20 years old, and mostly asian as well ...so I definitely can relate. From elementary school till high school whenever we would do the BMI tests I was always told I was "underweight". But I always felt like I ate a good amount (my friends would even say that I ate a lot) and I still do. Honestly, I think the low weight is just because of a fast metabolism and maybe some of my asian (pacific islander) genes since my mom and all of my aunts were about the same weight as me in their early 20s as well.
However, the last couple of times that I've gone to the doctor I've asked him if I needed to try and gain weight (just because I'd
personally like to be around 105)...and he's continually said that it's not necessary for me to do that. So if
your doctor said that you need too, I would definitely make another appointment and find out
exactly why you have to.
I'd also get information on exactly what types of nutrients you need that you may be lacking.
Well I asked about weight/height and she just looked at an BMI type chart and told me I needed to gain weight.
If your doctor just told you this based on the chart alone, without looking at your particular case specifically, I would definitely ask him again for more information or get a second opinion.