Nothing sells Book 1 like Book 2 ~ Valerie Douglas (2012)
Or Book 2 like Book 3.
In other words, marketing works but it’s much easier to gain traction when you’ve got a base of books to work from. Many indies find they start being successful level at book 5 or so. So, if you have professionally made covers that look good, professional editing and formatting, your reviews are good but your marketing doesn’t seem to be working, you should keep writing. There are very few breakout novelists, traditional or indie, so once you’ve finished one book, start writing book two while doing marketing around the first.
Not only will it give you more of a back-list to sell from, it will also ensure that you’re moving your career forward.