ALWAYS test before shooting. My cat, Kitty always ran high when we were dosing BID. Most of the time, her preshots ranged anywhere from mid 300s to high 400s. Over the 5 month period that Kitty was dosed BID, I bet we did not see two yellow preshots. BUT, on two occassions over that period we had a 98 and a 71 preshot. You can never be certain enough of a BG to shoot without testing.
I assume the +3 you are referring to, is +3 of her amps and that you didn't shoot. So, I am thinking it is really +15. Is that correct?
I agree with Denise, you need to reduce your dose and try to find dose that can be given at 12 hour intervals.
Keep a check on Danity, but I would not be surprised to see a sudden spike and a high BG. Remember, do not shoot the bounce. Even if you see a high BG and decide to shoot, you should reduce your dose. Most likely, Danity is going to react to the low BGs with her liver will dump glucosamine and a highBG spike will follow.
Please continue to test before every shot!!!
Good Luck!