A lot of your hubs are very promotional. Make money this, lose weight that.
That is a great hub - it would probably qualify as a great hub while in the program. I don't know the criteria, but I know the program. Write more like that, you might get accepted. Also I noticed your commenting is only at level 1 after a year @ HubPages. I was at level 3 within a few months. One of their requirements is that you partake in the private forums, and interact with the others in your group. Seeing little social activity is *probably* the main reason you got turned down, if I were to hazard a guess. Answer/ask more questions, talk in the forums, and comment on other hubs more often. I'll bet that'd change it.
As for an online portfolio...I had literally nothing but hubs (one hubnugget) online when I got invited. I've since started a blog of my own outside HP, but that's brand new....so it has nothing to do with portfolio.