anyone can press the render button and shit out glossy images. Show your design sketches and progress work. 

I think you have a very good quality renders, I know that's not particularly easy to accomplish, but the design of your portfolio is not even a half of the level of those pictures, the texts are too big and there is a lack of process or development of the concept of each project, like your graduation thesis looks not different from other of your projects, what makes no sense. 

Also I think is a little big to long, looks more like a powerpoint presentation that an actual portfolio. 

reads too much like a product brochure, or cd set, or...? no passion, a rote presentation. not inspiring.

Its quite long. The first thing that came to mind was if you really need a page that specifies "interior design".
On page three, the plan is colored in yet the ones after are not, though the coloring of the different spaces in the plan add no extra information, as its quite clear where the bathroom is, or that a space directly after what can be assumed to be the main entrance is an entrance hall. 
On page ten there is a render of a chair, then the reader comes to the realization that your showing him/her the table that you had designed, and not the chair. 
On page twelve there is another plan that is colored yet adds no extra information that the details of the included furniture could not already convey. My issue with the colored-in plans is that it breaks the grey-blue "aesthetic" you have built into the portfolio for no perceivable return.
After page 37 I'm still left wondering how you propose to keep the table from not falling over after a slight bump to its side.
These are my thoughts on the portfolio, not on the designs with in it.
I feel like your renders could use some more excitement. There are also too many of them, I felt that I had been scrolling too much. 

Thank you all for your suggestions!

I like the furniture.  Desk to go is good.  Keep going.

I like it. The fact that you got rejected might because of bad luck.

One way to know for sure the reason why you got rejected is to ask feedback from the school itself. They would certainly give you feedback about it.

Another way is to imagine it this way: If you're an interior designer and you got an email asking for intern in your office, what would you expect them to have? List them in a paper or a note, then go back to your portfolio. What can you achieve more in representing the best and the real you of yourself?

I wish you the best. Cheers!

I've seen better laid out Ikea catalogues, with better products in them. I already can't remember a single project and I just closed the tab two seconds ago. Show what lead to the final images, your process if there was any, and invest a bit of time and energy in laying out your pages, treat your portfolio as a design assignment.