Don't worry my Dear !
Here is a forumala for searching blogs for commenting , you just need to put your keyword in this fourmala where there is keyword is written in this formula and hit the Google search bar , you will find huge list of blogs of your niche sites. Make your own do follow blog list and ENJOY
Your keyword + do follow blogs in Google keyword+"post a comment"+"blog" keyword: blog "post a comment" –
If you have any confusion for searching ask me any time Dear !