Everyone is different and your height is a main reason for looking small...also dont forget the fact that alot of woman carry more fluid then others,so its not always what size the baby is.

I on the other hand am very big for what weeks i am.I went for my usual checkup few days ago and there were 2 woman there who were due in a few weeks and i was nearly the same size as them,i am 30 weeks. My last baby weighed in at 8lb 14oz,but I also had gestational diabetes and have been tested again and waiting for the results but it looks like im having another big baby where as my first pregnancy he weighed only 6lb 10oz. When people ask me when im due and i tell them September they are gobsmacked thinking ill say in a few weeks.And there is my sister who had 4 children all at 5lb odd.

So dont worry about how big or small you are,the size you look can be decieving,you also have time to balloon yet and usually do after 7 months