Buying domain

Hello! Currently have the free blog and I’m planning to buy a domain on WordPress. So, my website is now nomadpov.wordpress.com, and if I want to add nomadpov.com it says that it is already taken. I also have the option there as I see, to change the whole name to have it (.com). What happens to my traffic from the free blog if I change the website name when buying the domain? If I rename it as (for example) nomadnomad.com does the traffic remain the same?Thanks!