From the measurements you're coming up with, you'd probably do very well with a DSS small plate.
You're even smaller than I am (and I'm small), and I had a heck of a time even coming close with a standard BC. The one I ended up buying didn't really fit properly, and the tank was always slopping around on my back. The very first dive I ever did with a properly adjusted backplate and harness, I was completely sold. I've never looked back. I have put my BC on once, to try to do some gear testing in the pool, and I took it back off.
Especially if you think you might move up to doubles at some point, just bite the bullet and buy the stuff you can use long-term. You will have to cope with a weight belt or other weight system, because you're diving cold water. I use a weight belt and some weight on the cambands in pouches, and that works well for me. You'll also have to arrange storage for any safety gear you want to carry. I have pockets on my drysuit, and use X-shorts when I dive wet. You can buy pockets for the waistband of the harness as well. Some stuff can just be clipped off; an smb and spool, for example, can be put under your pressure gauge on your waist D-ring, or clipped off to the "stern" D-ring. Backup lights can be stored on the harness.
You might enjoy, if you haven't read it already, the essay on gear configuration HERE. You don't have to follow all the prescriptions, but it does go through the BP/W setup fairly thoroughly.
You're even smaller than I am (and I'm small), and I had a heck of a time even coming close with a standard BC. The one I ended up buying didn't really fit properly, and the tank was always slopping around on my back. The very first dive I ever did with a properly adjusted backplate and harness, I was completely sold. I've never looked back. I have put my BC on once, to try to do some gear testing in the pool, and I took it back off.
Especially if you think you might move up to doubles at some point, just bite the bullet and buy the stuff you can use long-term. You will have to cope with a weight belt or other weight system, because you're diving cold water. I use a weight belt and some weight on the cambands in pouches, and that works well for me. You'll also have to arrange storage for any safety gear you want to carry. I have pockets on my drysuit, and use X-shorts when I dive wet. You can buy pockets for the waistband of the harness as well. Some stuff can just be clipped off; an smb and spool, for example, can be put under your pressure gauge on your waist D-ring, or clipped off to the "stern" D-ring. Backup lights can be stored on the harness.
You might enjoy, if you haven't read it already, the essay on gear configuration HERE. You don't have to follow all the prescriptions, but it does go through the BP/W setup fairly thoroughly.