Hi - I am 5 ft 2" - most certainly not a size 8 though - but I had a natural birth - spent about 8 hours in water - tried to give birth in water but as things slowed down I ended up giving birth on a Dutch Birthing Stool on land !! I had no tearing and no stiches !!
My son was just over 3 kilos which isn't huge, but many first babies tend not to be huge any way. Subsequent babies are bigger because your uterus is more used to being stretched. As this is your first baby you will probably find he is tall, but not very fat, much easier for a natural birth.
My grandmother was about your weight and height and had 10 children (all natural birth in those days !!) My mother and her brother are twins - so she even managed twins with her small frame !
I also have a friend who is tiny and she gave birth naturally at home.
You need to be confident in your body to give birth naturally. My advice is if you really want to give natural birth a go (and if you and baby are healthy I really advise you at least give it a go!) try not to sit down or lie down too often during labour.
In the West we are used to seeing women with their legs up lying on a hospital bed, but this is not the best way for a natural birth. Your pelvis will stretch much more quickly and the baby's head will find it's way down much more quickly if you stand, walk or squat during labour.
I did quite a lot of reading on this before my baby was born and I am convinced that staying upright during my labour was crucial in giving birth naturally plus keeping my perinium intact.
Good luck !!