Forward Positions (Locks and Flankers)

Question
Hi. This is my first year playing rugby, and honestly, this is best thing I've done in YEARS. I love it so much!

My first question is about positioning for me. I'm 14 years old, 5'8" (maybe 5'9" since I measured), 150 pounds, and not front-row-bulky, but not winger skinny. My build is probably for a forward, but not a front-row. I'm better as a forward than a back, that's for sure, but again, not big enough for a front-row position. In 7's, I played Prop, and even Wing for a tiny bit, because I'm fast (not 15's winger fast, but I'm pretty quick), and Lock in 10's. 15's is coming soon, and I'm thinking I might be a Flanker, because of my build and skills (I'm a pretty good tackler). Does this sound right?

My second question is about Locks. In 10's, I was a pretty good lock (not trying to sound arrogant). When I playing with a different school at a tournament (funny story-- our coaches are friends, and they were down a few players), we were losing one scrum (we won all the others), and when I just pushed a bit more, we won, so I'm pretty confident as a lock. But, why do Locks have to be so tall? Every time I read a description of a lock, they're always the tallest players, and all the rugby-info sites say the same thing. Is it because they usually jump in the lineouts? My coach doesn't always put locks as jumper, props as lifters, etc. He'll change the forwards around depending on what they're good at. In that case, would I be able to play lock? Is there another reason for their height??

Thanks for your time!

Answer
G'day Geoff, all good questions my man, no arrogance in there at all.

To answer question 1 I reckon Flanker is the way to go, it sounds like you would be good at it and you seem to like it otherwise I assume you would have said #8.

In 10's go for lock , again it sounds like you are good at it.

Locks do need to be taller for lineout  jumping but sometimes a coach will make a lock lift a shorter guy. The point is that the end result is a guy in the air with the most hight possible, which ever works best, there is no rule. Sounds like your coach is experimenting a little which is ok as long as eventually a consistent arrangement is found to get a team flow.

Good questions, let me know if I can help again, thanks for asking