Insane 
And she’s considering possibly going up to 6 or 6.5K! Whether she pushes it further than that one day, even she doesn’t know.
Considering what she has been through, her desire to have bigger boobs is so strong that I have doubts she will stop there. I'm not sure if she has acknowledged having boobie greed one way or the other, but her obvious pleasure and happiness, combined with still wanting more, suggests Brittany would be totally delighted experiencing all the huge boobie problems that they naturally will create.