It's probably worth running the HTML through tidy to get cleaner XHTML and then spending a little while trying to get http://code.google.com/p/epubcheck/ to be a bit happier. In general, EPUBs that "pass" epubcheck have a better chance of working interoperably in a lot of EPUB readers.
I sympathize; I was in a simliar situation around five years ago.
There are three things I've done which have been responsible for literally every job I've had in the last decade. In order of importance, they have been:
1. Know people.
2. Engage in the FOSS community.
3. Challenge myself.
That's it. Now, the interesting thing is that if you reverse this list, you get the steps you need to get a new job:
3. By challenging yourself, you will increase your knowledge base and become a better coder.
2. Find an project, tool, or subject that interests YOU. Something YOU would find useful and rewarding. Whatever it is, write it and RELEASE IT. If there's a project that already does what you want, start contributing. Help other people use it. Write documentation. Anything. Whatever it is, RELEASE IT. Doesn't matter if it's something a hundred people worldwide will find interesting - you'll get their attention, which leads to…
1. Knowing people who can get you jobs.
I cannot stress this enough: RELEASE CODE. The great thing is that you can usually get your employer on board with this. If other people use it, they can contribute features and bugfixes back, which they can make use of. It's like having programmers work for them for free.
The fact that you have this ambition at all puts you at a significant advantage over other programmers. Keep hold of that drive.