I wouldn't give up on it so easily Warr. When I first started tanking, we were all back in BC. I delayed tanking heroics for WEEKS because I was so worried about not being a bad tank. I spent a lot longer on normal instances than I really should have, and would only run my first heroics with the guild, that's how nervous I was
I researched all the numbers I needed to have, and made sure I surpassed them all before I would even get near a heroic. But once I finally ran in to my first pack of heroic mobs, I remember thinking "hey, that wasn't so bad!" With each new heroic, I gained confidence until I had a list of random people from the server asking for me to join their heroic groups when I logged on. It was great.
Unfortunately, I never did get to a raid tanking level before Wrath came out. This time around, I wasn't afraid of heroics, but I did go through the same thing in raids, even worse this time. I felt like I had 9 or 24 other people depending on me. I ran numbers even harder, got my stats about 10% above where they needed to be, and finally stepped in to my first raid.
I was terrible.
I ruined the whole run (luckily it wasn't a guild run).
But after running a few of the lower level raids with the guild, learning fights, and improving my gear, I became a lot more confident.
If you really enjoy tanking, just stick with it, and I'm sure you'll be a very capable raid tank someday!