The younger sister is worried about dog attacks. The older sister says this:
There's no need to worry so much. You'll reach the point where you end up not going anywhere anymore.
I'm not at all sure about the meaning of the second sentence. With the translation I gave above I would have expected just なる rather than なってる. With なってる I feel inclined to translate it as "I've reached the point where I've ended up not going anywhere anymore. This seems less likely given the context.
So, my main problem is, is the older sister talking about what will happen to the younger sister (future tense, I'd expect なる）or is she talking about herself (already attained state, なってる)?
Due to the above confusion I'm also not sure whether もう means 'already' or 'anymore'.