I'm sorry that you didn't get the score you hoped for and needed. As Platypus has said you should possibly consider applying for those courses that don't need the GAMSAT.
However, that's no reason not to try to improve your GAMSAT for next year if you want to try. You said that you took an online course; may I ask who this was with and what it involved?
I must admit that I did very little direct preparation for sections I and II, focussing on section III and scored much better than I had anticipated. I credit this to the fact that since completing my full-time degree (in 2001) I have constantly been studying purely for interest with the Open University doing Humanities and social sciences mostly and therefore been forced to learn to read carefully and write lots of essays and do lots of exams.
Obviously you don't want to do 6 years, but have you considered taking some sort of "foundation" course in either the humanities or social sciences? The Open University provide one in both: A103 Introduction to Humanities (
http://www3.open.ac.uk/courses/bin/p12.dll?C01A103) and DD100: Introduction to the Social Sciences (
http://www3.open.ac.uk/courses/bin/p12.dll?C01DD100). I have studied both and either is likely to help with both section 1 and section 2. The OU will also offer study skills courses (for no extra charge) if you are register on any of their courses, type and frequency depending on the area you live in. The next start date for both these courses is in February and if you happen to have any tesco club card vouchers lying around you can use tesco deals to part-pay for the course (as part of their widening participation scheme). Just in case you are wondering I am in no way connected to the Open University (except for being a very satisfied student)!
There are alternatives too – you could read a variety of sources for example anthologies of short stories and poems – ones with good commentaries so you can get an idea of meaning, or a good book with an accompanying study guide (e.g. York notes, or something similar). In terms of essay writing, have you considered once a week looking at the top story on the news and giving yourself half an hour to write about the issues involved (without reading the story) and comparing what you thought with how the journalist wrote about it and getting someone else to read it for you and comment (I'm happy to do that for you if you like via e-mail).
Basically, I understand how you feel – being older than the average GAMSAT student (based on observation at the hall in London) at the grand old age of 31 I've had plenty of opportunity to become familiar with disappointment in both tests and job applications. However, if this is something you really want to do keep going – success is always sweeter when you have had a few knocks, although that doesn't make going through the knocks any easier.
Please feel free to PM me if you like.
Stephen