Hi Albere
It sounds like you've done some good work to progress as far as you have. I'd suggest to keep going and not give up, if what you've been doing has worked then keep doing more of it.
I've seen on many an occasion that it does take time and perseverance to jump from the second page to the first.
Try performing a competitor link analysis if you haven't already, look for any linking opportunities. See if you can improve the anchor text of any existing inbound links that you have.
Check your on-page and on-site attributes with the SEOmoz toolset. Ensure those keywords that you are targeting and included in your Meta Title, Description, H1 tag and throughout your page content (without over-doing it, everything in moderation).
Have a read of "A New Way of Looking at Ranking Factors" and check out the periodic table of ranking factors within it.
Keep producing fresh, relevant, interesting valuable content and share it socially across the likes of Facebook, Twitter and Google+. Do some online PR and share your content, this helps with acquiring new natural links.
Hope that helps,
Regards
Simon