What is the problem?

I need someones expertise.....I notice that when I include pictures in my post, my font is always "bold". When there are no pictures (as this will probably turn out), the writing is decent size and "regular", not "bold". No matter what I try to do to fix it, nothing seems to work. I honestly don't like the small, bold size that comes when I include pictures. To me it's not easy to read. Any thoughts as to why this does it and what I can do about it. I am using a Mac...if that even matters. 

With Joy UNquenchable,