In google analytics, you’ll see which search engines are directing traffic to you and also which keywords are getting you hits. Also there are many other handy analytics google provides you with If you’d like me to go through this with you via phone or msn, let me know and we can make a plan.
Dont beat yourself up to much about the SEO on your site, some of the things are fine and some things you can add or change but I’d first look at what kind of traffic you getting and why, and then start working SEO’ing your site according what traffic you looking for. This will take a bit of time to get right.