You just opened up a can of worms. Get ready to receive hundreds of posts with different answers LOL
To me its when your hair at least touches the bra strap. That's good enough for me!
I agree with everyone's post so far. It's when your hair touches your bra strap as long as your bra strap is where it should fall naturally on your body. I know I've seen some hiked up bras with people whose boobies must come out of their neck, but I've been lurking...err watching you Ediese and I know you've got to be BSL chica, claim it!!
You're under your shoulder blade so that's bra strap to me.
You know I have seen some pictures where some peoples bras are almost up to their neck erplexed. Then they say they are bsl when really I think they'd just be apl. But if your bra is in the middle of your back like most bras then I'd claim it when the hair is touching the top of the bra.
Looks BSL to me. I think we're growing at the same rate. I'm touching the top of brastrap too now.