First of all, congrats on the 770!! You actually tied my score. Looks like I need to retake now
As for the IR score, the best advice I can give you is
don't worry about it!If you got 2/3 correct, you can expect a score somewhere in the 5–7 (out of 8) range. Why the variability? While IR is not computer adaptive, there is some adjustment in the score based on difficulty of the questions you see. It's possible that you just happened to see some of the more difficult IR questions, in which case there will be some forgiveness in your score.
But really, it does not matter if your IR is "horrible". For starters, Business Schools don't yet know what a "good" or "bad" score actually is. Until they have several years of data and can see whether IR scores actually correlate with B-School performance, they're just not going to care that much. Especially not if you rocked the main test with a 770. There
is a correlation between your out-of-800 score and your B-School performance, so that's what they're going to care about.
So shake it off, congratulate yourself for being done with the GMAT, and move on to the rest of your application!
For those of you who still need to test, take a look at
https://www.manhattangmat.com/ir.cfmfor some good IR info.
Cheers,
Mark