MY RSS feed doesnt show half my site's posts

Hi

My feed shows only a section on my site, from other sections apparently theres no RSS, how can I fix it? heres my site

http://www.medicoslideres.com/

my rss feed: http://www.medicoslideres.com/feed/

check how the feed only get posts from the blog and the tips sections, but nothing from the news item section (check most of the main page posts and you’ll see dont appear on the RSS feed)