It is so easy to fall into the regrets trap...if only I had started earlier...if only I had taken that class...if only I had not blown off that editor....if only I had listened to X...Whatever you are writing and whatever stage you are at, don't stop because of nagging regrets.
Remember: No one else knows, or even really cares, what all happened before The Book became The Book. Only you know. If it started as one kind of book and morphed into another, your reader doesn't know. If it has taken you ten years and you're half way there, your future reader doesn't know. And as you get closer to the book's completion, you, too, will forget all the side-winding, bizarre oops-moments.
Your reader's experience begins when they pick up the book and start to read the first page.
So start again today, and take the reader on the journey you want to take them on. Never mind the woulda, coulda, shoulda.
You are here, now. Lead the way.