Welcome to the Colony, Christine.
If you can afford to hire professionals to help you with editing, formatting, book cover design, promotion/publicity/marketing, then you'll be more successful at self-publishing than most writers who do everything for themselves. The reason that most authors seek a traditional publishing deal is to have a publisher do that tiresome work for them; it's why I've made 400 queries in the last four years!
Having said that, these days a book publisher expects their author client to be an all-singing, all-dancing self-promoter running a blog and social media profiles with hordes of followers and a willingness to attend public events to meet the public. An agent might be disinterested in representing you as a shrinking violet. In these days of limited attention spans and multiple distractions, it's all about making a quick sale of your book to potential readers—interesting them in the concept via an
elevator pitch and trading on your image as an author.
My attitude is, that if a book company expect you to do all of that, and for a mere 15% of the sales of your book (minus 15% to your agent), then why not do it for yourself and keep most of the profit?
Self-publishing ebooks and making money from it isn't easy, though, for you have to find ways to make your novel stand out—the dreaded process of
discoverability. It's likely that your book will simply disappear among the hordes of other titles on Smashwords and Amazon. In 2013-2014 I self-published 44 books online. Last year, I edited them all and joined the queue on Smashwords to upload the corrected versions. Intrigued as to how many other writers were doing the same thing, I made a note of how many volumes were on the site when I started. It took me about an hour to get my new books online, waiting for approval by their editors, and in that time there were 400 new books published. I've just checked their total and it stands at 464,917 books! How would a reader choose your book from half-a-million others?
That's the key problem to solve—your book is a snowflake in a blizzard! I'm returning to self-publishing soon: just call me Scott of the Antarctic....