So like most of you in the wordpress world I too struggled with the annoying fact that you can't add paragraphs in the visual editor of wordpress. Even some seem to have trouble with HTML cheats and for the life of them can't add or format paragraphs.
A really simple solution that I came up with, is just to add a new paragraph with a letter in it ( I use P to keep easy track of everything ), and just change the color to your background so it's invisible.
This is my first sentence and I want the next one following it to be 3 line below it.
and now this sentence will appear three lines below it. I will change the letter P to become white and the blog will look professional as you want.
Easy cheat until something else comes along.