If you want to see only posts from blogs you follow on Tumblr, you can use the "Following" tab on the dashboard, it's usually on the top navigation bar. Clicking on that will show you a feed of posts from all the blogs you follow, without any recommended content. You can also switch to the "Latest" view to see the most recent posts from the blogs you follow, this way you can avoid seeing any recommended posts. This should help you stay focused on the content from the blogs you're interested in, without the extra suggestions.