I do understand your concern about your biography. Like you, I started my career somewhere else, and to my disappointment circumstances came in the way and it was discontinued. What grief I went through. I could not bear to identify with the tasks that generated my income. Luckily, things changed, and as an editor, I’m no longer ashamed about talking about my work identity.
As for your book, your background in banking does not serve any purpose. Any potential readers, that is, buyers, are looking to see whether you are qualified to write this particular book. Experience in the field you have written about, however domestic or unprestigious it may be, does actually give credibility. What you worked with more than a decade ago will, at best, confuse the readers and, at worst, make you seem like someone who is not the right author for your book.
Your biography is not an attempt to summarise who you are, but a way of convincing your audience that you book is written by someone who knows what they are doing.
Looking forward to your next draft,