Hello Rosa,
Thank you for your kind words...I am happy that the article is useful to you : )
As for your question...it isn't that you cannot break into investment management having worked in the back office, it is just that it is more difficult. The reason is that people in the investment business begin to compartmentalize you - incidentally, this is very similar to the behavioral finance bias 'mental accounting' - and once you are in a compartment it is difficult to escape. There are three ways to escape the compartment and all of them require a drastic on the narrative that is forming around your career. The first is to get your CFA charter, which allows a new story to be told about you and your potential. The second is graduate business school or an equivalent (Masters in Finance or Economics, for example) where you have achieved at a high level (think: high grade point average). The third is to be able to demonstrate that you have the skills necessary as demonstrated by your personal research examples, a website, or something else. Best of all? All three. In my case I chose to go to graduate business school, achieved much; had a personal website with my research examples; and had passed Level 1 of the CFA.
In terms of what type of a position to look for...any work, including internships that requires you to do analysis of some sort, even if this is not securities analysis. In my case, I was an intern at a pension consultancy while in graduate business school. My undergraduate degree was in economics, and by the time I secured my internship I had already demonstrated to my fellow classmates that I was hungry. This meant that I could utilize my school's alumni connection to get the internship.
Best wishes for success!
Jason