Why does my site still not have PR?

well, to be honest, u have done little or none SEO jobs on ur site, ur content is pretty small, if u have about site:youtsite.com about 500 links, maybe it's probably time for u to get PR jumped.
just my 2 cents

 

Better focus on getting quality backlink than quantity backlink

 

I think the most easiest way of getting PR is by stopping worry about getting it. We should only enjoy on the google quality links we are getting, we should enjoy the relevant traffic we are getting. Let google update the toolbar whenever she likes, leave her alone.

 

Focus on building more links from more reputable sites especially those Web 2.0 ones.

 

Maybe stop worrying about page rank (especially TBPR), and worry instead about SERPS.

Pretty sure none of this is true. In fact, I would go so far as to suggest that your 5k links in 6 months are what's causing it. Google probably noticed that your site didn't have any reason to have 6k links, suspected you of selling links, and turned your rank down.