Since ypu mentioned sizing issues - a pricier option might be Aqualung's Soul model which is a ladies BC available as small as XXS, They have a sizing guide on their website - another option might be the Pearl which is a jacket style in XS The Lotus only seems to go down to size Small.
Notice the Wave also which is a less expensive unisex model as small as 3XXS but it lacks weight integration so you will always have to use a weighbelt/weights. Wouldn't be for me,,,
BC Size and Lift Chart - Aqua Lung US - Recreational and Professional Scuba Diving Gear
It sounds like the problem will be availability in your area so maybe start out with the Tusa since you can acquire it easily and change if you need to later,
Also you might check to see what/if an internet reseller can do into your country including taxes/duty etc. From the US one option might be
www.leisurepro.com who does ship worldwide afaik - in Europe possibly
diveinn Scubastore will be a better option.