Just based on what you've described, I'm going to say that your hair is definitely not coarse. Texture (width) seems to play more of a role in protein sensitivity than porosity. When I first found this site I also thought that my hair was between medium and coarse because I could see the individual strands. Then I started seeing that my hair didn't act like medium-coarse hair at all- for example, my hair couldn't get enough protein. I finally caved and got the hair analysis, which confirmed what I was starting to suspect- may hair is fine. I can still see the individual strands, and I even have some individual strands that are definitely closer to medium or coarse texture, but the majority of my hair is fine.

3a/f/iii
Modified CG since 11/5/11
CLEANSE: VO5 Vanilla Mint Tea Clarifying, DevaCare No-Poo, CHS Treatment Shampoo
RO: DevaCare One Condition, SS Caitlin's Conditioner, Mop Top Daily Conditioner
LI: SS Repairing Protein Treatment, CHS Silk Leave-In
STYLE: Re:Coil, Curl Keeper, Deva Ultra Defining Gel, Curls Rock Amplifier and Strong Hold Mousse, Sweet Curls Elixirs Okra Gel and Hard Hold Gel, SS Curl Enhancing Jelly and Firm Hold Gel