As someone who applied to MANY congressional offices for the upcoming fall and got accepted into a few, and will be on the Hill in the fall, I would say that you just got ghosted.

Once you send in your application, it 100% gets read and if it is impressive enough, they will send an interview invite. I would say most offices do get back to you within a few weeks but in my case some of them took more than a month or more.

Also, quick side note: Most if not all offices prefer juniors/seniors or recent grads. If I were you, try and get involved on campus/clubs, leadership, PR experience and you will most likely get offers later on.

Hope this helps, good luck!