I'll back up what tjhooper has said. If you pick competitive terms to write about, you'll find it very difficult to rank well in Google, which is where the money making traffic comes from.
I've just had a look at your hubs. You need to be a little more prolific with your writing. I joined Hubpages 3 months ago and I have found that I need to write about 6-10 hubs to get one which performs really well on Adsense, and that's with keyword research!
For each hub you write, you need to research your keywords and go for long tail keyword phrases of 3-4 words. These are much easier to get ranked highly in Google, and will bring in traffic.
Try breaking up your text too, put different paragraphs in separate text boxes, with your chosen keyword phrase in the title. This will also increase the number of Google Ads which appear on the page. You only have one text box, and if you had more, you would get more ads, and give your visitors more to click on.
If you want to increase the chance of earning money, add in Amazon or Ebay widgets to your pages, this brings in good income, and makes the pages look more attractive although you do need to have a healthy number of daily visitors in order to get regular income.
Also source some images to break up the text. If you manage to attract visitors, the last thing you want to happen is them to click straight off. Large blocks of text are often off putting. Besides, many people just skim read, which is very difficult with large blocks of text.
You only have a few seconds to capture someone's attention, and images are the best way of doing this.
Also try not to have headings underlined. Bold text stands out more.
A lot of points there, I hope that these will help! Don't give up on Hubpages though, there is good money to be made here!