I've always wanted to write novels. I never had much interest in short stories. Years ago I attempted my novel, got completely lost and frustrated and said to myself, "I'll just write short stories first. They're bound to be easier. When I get good at that I'll go back to my novel." Well, I tried that and hated it. (I did get something published, but I wasn't happy.) I finally decided to go back to the novel, but this time I did a lot of research first on how to write a novel. Suddenly everything is coming together much better.
On the one hand I think if I had read all that material on "how to write a novel" earlier, it would have been much easier. On the other hand, writing short stories wasn't a waste, I got a real honest-to-god publishment under my belt, and I've written stuff - anything - every day. So maybe that's what's honed my skill to attempt the novel now. You're even further along than I am, having published thirty stories, so I don't think you need to strive to write better short stories. I think it is time for you to write the novel. You are bound to be frustrated as you're sort of starting back at the beginning as a noob. At least that is how you feel because a novel is a different animal from a short story.
Think of it this way: you got your pilot's license. You fly a little single engine airplane on clear days for a few years and build hours in your logbook and become a pretty good pilot. Now you want to be able to fly "on instruments". That means in clouds where you can't see up or down outside the airplane. It is a whole 'nother skill. When you first get in the airplane with the instructor you feel like a complete beginner again. Oh, you've practiced "under the hood" (simulated) some, it's required, but you have never really flown on instruments successfully. You will go through a whole new iteration of feeling the same old doubts, fears, frustrations as you did when you were a beginner flight student.
So don't think of yourself as a beginner novelist, think of yourself as a successful storyteller, and you're just embarking on the next level. You're a good enough pilot now to go for your instrument rating. You're a noob at flying on instruments but you've got the basic skillset to get an airplane safely up and down so you're actually plenty ready to start this training, no matter how idiotic you feel with your instructor, who is good enough to do aerobatics in clouds. Feeling like you aren't good enough to write the novel yet is to be expected, and completely normal.