It sounds to me like you may have been meeting with scam artists, or are severely confused about what the actual terms of being publishing are.
When your novel is published with a reputable, honest publisher, the publisher provides the cover. Period. Not only are you not required to have a cover, even offering or mentioning a cover of your own design is seen as unprofessional, since it betrays a lack of knowledge of how the publishing industry works. There is no real publisher that would ask you to provide a cover, and publishers will not usually even look at a cover that you provide.
When you self-publish through Amazon, Smashwords, or any other reputable self-publishing service, you provide your own cover. Of course, in this case, the self-publishing service is emphatically not the actual publisher of your book---they just provide a marketplace and a clearinghouse for self-published works. Your are your own publisher in this case, which is why they call it self- publishing.
So if you are actually in talks with a real publisher, don't bother with a cover. They will provide one. However, reading between the lines of your post I wonder if you aren't talking to a scam publisher which pretends to be a real publisher, but expects the authors to foot most or all of the cost of producing the book. If the "publisher" that you're talking to expects you to furnish a cover, pay for editing, or do anything else of the sort, then run away quickly. Paying for those things is the entire reason that publishers exist (from the writer's perspective), so if you're being asked to pay for those expenses then you're better off simply self-publishing.