As a fellow self-taught developer, I feel your pain. I've been there, many times.
However, there's no reason that you can't also teach yourself the necessary CS fundamentals required to ace these types of interviews. There are plenty of people out there who have done it. "Cracking the Coding Interview" is a great book that if you dedicate enough time to it will help you totally nail those questions (once you have the fundamentals down).
The real secret is to avoid the technical interview altogether. How, you ask? Networking. And not the typical schmoozing type, either. A quick way to start is just to connect with every single developer at your current job. As they make their way to other companies, they're going to either be in a position to hire or at the very least able to strongly recommend someone (and many companies don't actually do these crazy white-board interviews).
However, there's no reason that you can't also teach yourself the necessary CS fundamentals required to ace these types of interviews. There are plenty of people out there who have done it. "Cracking the Coding Interview" is a great book that if you dedicate enough time to it will help you totally nail those questions (once you have the fundamentals down).
The real secret is to avoid the technical interview altogether. How, you ask? Networking. And not the typical schmoozing type, either. A quick way to start is just to connect with every single developer at your current job. As they make their way to other companies, they're going to either be in a position to hire or at the very least able to strongly recommend someone (and many companies don't actually do these crazy white-board interviews).