Adsense is very vague when they reply to your application. Insufficient content doesn't just mean not enough content.
Are your articles written all by yourself and not copied from elsewhere?
Adsense wants original unique high quality content.
Getting into Adsense used to be easy, but now it's harder than ever.
Also make sure you have a TOS "Terms of Service" About Us, and Privacy Policy Page.
The TOS and Privacy Policy is a must have and you won't be accepted without those.
Good luck and I hope you can get into the program.