As I said at the top of the page from the DR Embassy web page for Canada.
http://www.drembassy.org/english/index-Tourism3.html
They have a section , link above for travel with those under 13. Going there will give you what I posted. The Embassy is in Ottawa, 1-613-569-9893.
I would think with a long form birth certificate and no father named you are pretty much the only person of concern anyway, though you might want it translated into Spanish.
Also note it says "Concerning children 13 years old and under traveling alone or ***with a person other than a parent ***friend, uncle, aunt, sister, brother, niece etc.) should have a passport and a special permission from the parents."
So you are the parent and OK by the looks of it.