@jakebasile, Whether you take manyxcxi up on this or not; I think s/he is making a great suggestion here. 12 interviews and zero offers is a lot of interviews. A few feedback style interviews with some candid feedback might do you some good. Technical skills aside it is possible you just are not interviewing well.

Also a couple of somewhat related questions.

1) How well are you at reading the interview outcome? Do you leave these interviews thinking you will be made an offer or do you leave with a pretty good idea that a no is coming your way?

2) Rather than waiting for a rejection and then asking "why not", have you tried asking for the "why not" during the actual interview? At the end of almost every interview someone will wrap it up saying something along the lines, "Do you have any more questions?" I have had plenty of candidates ask me (and I myself ask if I'm the candidate), "What do you think I could have done differently today to improve my chance of success with your organization?"

This is usually met with a more honest feedback than the ask after rejection for numerous reasons.

1) Less HR cover my ass BS; after the rejection companies are worried anything they say could be used to sue them.

2) More people in the room so you may get more than one perspective.

3) You haven't yet been rejected so you may also hear some positives; "Well you really impressed us on X, but you could focus more on Y." This can help you to play to your strengths in the future as well as areas you need to work on.