So you've used about 10% of your original 12.6g. That means you have about 11.3g remaining. My recollection is that Dignitas uses 10g, so unless you're very large (body weight affects doseage) you're probably good to go.
But I wouldn't do any more tests. If it were me looking at those two bottles, I'd be confident I had just enough to ctb, but no margin for experimentation.