"When you have to shoot...shoot...don't talk". That's an epic dialogue from an old Hollywood film from the 1960s titled, "The Good, The Bad and The Ugly" which is part of a series of three films known by their genre title, "The Dollar Trilogy", that became a huge international box office hit.
My advice would be to start writing and stop planning any further but first, let's understand why you haven't been able to start writing so far. It could be due to the fact that you still haven't identified the genre and subject of your novel. Honestly, you won't be able to start writing your novel for as long as you continue to neglect the genre and subject of your story.
A novel is different from a short story in the sense that you clearly know the entire plot in a short story since it is based on one or two events around which the story is woven. On the other hand, a novel is like a chronology of events over a long period that can stretch across decades and generations.
Is it possible for any author to imagine all that and write the novel just like he would write a short story? That would be very unlikely. Even a thriller which is not as chronological as many other genres of novels, would require a long time to write if not for anything else, then at least for the sheer scale of elements that the thriller would cover.
As a budding writer, what else have you been doing to write a novel other than just planning? For that matter, what's all this planning all about anyway? You're not going to write a detailed project report or a research document. What you'll be writing is a long narrative that you will imagine and re-imagine endlessly even as you write down the different episodes.
Novels are conversational and are built around the characters that the author is able to imagine. Think of the conversations that these characters will have and how that will drive your story. Unless you experience that in your mental universe, your novel will remain in the planning stage. So, start writing and stop planning.