I'm a couple of inches shorter than you. Blanche bb will be fine on your frame. I have it on the shortest setting on the strap. If you don't carry too much. And you want a small neat, slim compact bag, really recommend this one. The non detachable strap hasn't so far been a problem. It fits my essential's:-
6 ring keyholder
Rosalie coin purse (used as wallet)
Mini pochette
Slim compact mirror
Large mobile phone (in front pocket)
I don't think you can put any other SLG's in there maybe a couple of card case on interior 2 side pockets slot. The lock is easy enough to close. I tend to do it by holding the slim base of the bag and push the lock in, is easy enough. I use it for dinner events, theatre or meet up's where I don't need to carry much or be intending to need to put things in whilst out. All in all great little bag