The float test can be unreliable. I've seen instances where someone's hair floated, but they later found out it was actually normal or even low porosity. Instead, I would look at the strand test and how your hair usually behaves. The link Ml001posted has good info. If you want a definitive answer, you can also order a hair analysis from here.
CG since 11/2011
2c /3a F /Mii, low porosity

Fall Products /Routine:
Clarifying: Herbal Essences Tealightfully Clean
Low Poo: Renpure Luxurious Argan Oil
CO: Suave Naturals Tropical Coconut or Daily Clarifying, V05 Strawberry or Kiwi Lime
Tresemme Perfectly (un)Done, Cure Care, V05 Kiwi Lime Squeeze, V05 Strawberry, Renpure Brazilian Keratin (old formula),
PT: IAGirl's as needed