Philli, I have a hub about publishing a children's ebook. I think you have to go to my profile because I'm never sure if we can include links to our hubs in our answers here.
Publishing my children's ebook and print book was enormously rewarding, BUT I have lots of thoughts to add. I published about 2 years ago with bookbaby and never looked at their helpful promotion guidelines until yesterday!! I found out that I could have gotten free reviews by respected reviewers. So I definitely am going to follow that avenue immediately. When I read that I thought, "Opps, what if the review is bad?" No worries. They will give you a review and if it's a "4" or a "5", they will list it on their website, otherwise, they'll just send you their response. I am only now exploring this. You're exactly right PROMOTION is EVERYTHING. (Well not everything). (Right now I'm reading "77 Ways to find Readers for Your Self-Published Book" - excellent).
If at all possible, I might think about getting a print version. Until I got the print version, I had ZERO interest, even from friends and family. Of course, I had to take a loss because I only had $600 to spend for 100 copies of a flimsy glossy paperback. (24 color pages) BUT my book is at Lefty's in San Francisco on Pier 39. (It reaches a niche market of little left handers). I wanted to go to kickstarter for funds, but the person that was going to make a video for me, didn't have time. (PS udemy.com has information on making a great video for kickstarter. I've given $5 here and there to various kickstarter campaigns which actually got funded. I wish I would have followed through with that and got enough funds for a nicer print version.
Bookbaby is the publisher I used for the ebook even though I could have done it myself. Bookbaby will get you into the Apple store, Barnes and Noble for Nook, and lots of other places that going with KDP can't get you. Bookbaby has an EXCELLENT guide to publishing that is available online before you publish (I think I have a link in that hub) AND, at the time I published, they had EXCELLENT phone service for any questions.
I wouldn't worry too much about selling right now because once you have your book out there, it's there forever. Even two years later, I'm hopeful that if I FOCUS on my book and not 92 other things, it will sell. Visit "Lucky's website" from my hub and feel free to email me about the mistakes I made along the way and what I would do differently the next time. Billie :)