Moz are the third party service. If you think there is problem with website then check google analytics and google search console. And about DA check that on different websites like SE ranking, Ahref etc etc..

These day google showing only 100 result on its SERPs your pages probably in those over 100 pages that google have not showing To rank those pages include Keyword that people has been searching on google search bar for that you have to do keyword research

All these process might be hard for individuals consider hiring professionals