It boils down to experiences and stories.
On your resume, you list periods of employment. Under each job, you list what you did, and big projects you worked on. So it might look something like this:
When you go for an interview, they're going to look at this and say, Ok, Sadrabbit has 3 years' experience in IT. Now I want to know what he can do. So you're going to get questions about your experience:
"Describe the work you did on tech support. What were your responsibilities? Did you manage yourself? What initiatives did you start to make things more efficient? How did you handle difficult users?"
And you're going to get questions about specific projects:
"Tell me about this ticketing system you worked on. Whose idea was it? Were you the only developer? What technologies did it use? Describe the biggest challenge you faced on this project, and how you overcame it." (Be prepared to answer that question for every line of past experience on your resume.)
So your internship is fine, as long as you can describe specific things that you did. It's not enough to say, "I did an internship for computer stuff with Company X". Have a list of problems you solved and projects they put you on. Tell the story of your internship, like "I came in and the help desk was a mess, but we got things cleaned up by the time I left". Think through the business challenges your company was facing, how those challenges affected your work, and how things ultimately worked out.
(And if things started bad and stayed bad when you left, don't complain, and don't throw people under the bus. Just take a resigned tone and show how you tried. "We tried to clean up the help desk ticketing system, but the boss said we didn't have budget for the new software, so I tidied up the code and saved it in the repository. Hopefully they have the budget next year, and it's ready to go!")
I would still recommend having at least 1 passion project you did on your own time that you can talk about. Whatever really interests you in IT, the kind of thing that you'll skip video games and parties to work on out of sheer curiosity. (And if you aren't so interested in coding or creating that you occasionally do it in your free time... then maybe take a serious consideration about whether you want to do it as a career.)
TL;DR You don't need a full portfolio of projects, you just need specific things that you've accomplished either at work or on your own. You need to be ready to tell the story of how you did it, and what you learned from the experience. Projects are the language of IT--state the problem, solve the problem, implement the solution--and make it easier to communicate to others what you've done.