This is only your first novel. You plan on writing until the last breath escapes your lungs, right? You can’t imagine what it would feel like to not spend the vast majority of your time living in a fictional world with people of your own creation, right? You want this to be a career, right?
So, cut yourself some slack. You don’t have to stuff every great idea you’ve ever had into this book. You have all those other ideas floating around in your head, think how good they’ll work together even if your brilliant ideas don’t fit seamlessly into this one.
The only promise you made was to write the best novel you possibly could and do justice to your characters. Focus on this story, the rest can wait, and tell it perfectly.