Move my blog archive pages to the blog page URL

Hi

I’ve searched real hard for a way to move my archive blog pages to my blog page. Right now my blog is set to a specific page: mydomain.com/blog, but my archive permalinks are still: mydomain.com/2014/15. And since I have different sidebars for my homepage and my blog, this is messing up the user experince.

There must be a way to make the archive pages get the /blog/ prefix, like: mydomain.com/blog/2014/05

If anybody knows how – I would be really happy!

BTW – I’m using the fashionista theme from wordpress.org: http://wordpress.org/themes/fashionistas

Thanks,
NW