Actually it's not. 110 lbs. at 5'4" gives you a BMI of 18.9 which is within the normal range of 18.5-24.9.
No that can't be right. I'm 5'2" and I was once told that my normal weight should be around 120.
That would put you at a BMI of 21.9 which is right near the middle of the normal range. BTW, I don't agree with this normal range stuff at all. I think most people look much better if they are closer to the top of the normal range and maybe even a bit over.
according to: http://www.halls.md/ideal-weight/body.htm, the medical recommendation for a girl that is 5'4 is 111 - 146 lbs, so its really far down there.