Formatting eBooks can be a pain in the backside. Here are some quick pointers for doing it right the first time.
1. Don't double space after periods. Use Find/Replace to correct this throughout your document.
2. Select paragraph option from the top of the Word menu. Delete paragraph symbols showing between paragraphs.
3. Open the Normal stye pane in Word on the top right. (You may wish to proceed a chapter at a time at this point.) The settings are alignment - left, body text, and the rest are all at 0 values.
4. Under Special, make first line 0.2, and enter line spacing at 1.5.
5. Do a spell check again for your entire document. Check for spacing errors, and be sure to use the Kindle preview option to see what your final document looks like.