honestly u can play any position u feel like I would say probs number 8 but it really depends what your good at in general a prop is big strong and slow there numbers 1 and 3 a hooker is shorter but still big and strong but they can be fast or slow this is #2 second rows are tall and strong #s 4 and 5 the back row or the flankers and number 8 and fast strong and good tacklers #s 6, 7 and 8 the scrum half has good hands and is usually one of the smallest in not the smallest on the field #9 the first reciver is strong to break through the line but is also a really good kicker and a quick thinker #10 the centers are strong and powerful there fast and usually the biggest backs # 12 and 13 the wings are usually small and fast # 11 and 14 the full back is fast and a really good catcher #15 see where u would fit in best but there are just what the people playing the poitions are like I am tiny 5'2 54 kg fairly fast and play flanker im about the same size as our scrumhalf im strong for my size not the best tackler but a lot better then I was I play open side flanker so u can really play any position u feel like
You are big. You should be a forward but because of your speed and size you should be outside center.
You play wherever the coach tells you to play. If he says "I want you to play open side" you don't say "No, I'm a no 8". Even established international players get selected to play out of position.