I want to quit

This is my 4th child. She's 8 weeks old and still nurses every 1-1.5hrs for a total of 15-20 minutes. So in reality I'm nursing every 40 minutes. I'm exhausted. I'm over it. I nursed every other kid well past the age of 2.5yrs. Not sure why I'm feeling done already, maybe because I had a c section and didn't bond with her for several hours after she was born? 
Now it's just annoying when she wants to eat and honestly I grit my teeth. I don't know what to do. Suck it up? Or quit because it's starting to wear my mental health down? I have three other kids to tend to and it's impossible when all she wants to do is eat constantly.