Don’t be too obsessed about your domain authority score. It’s just a number that shows how strong your domain is, compared to other domains that exist in the Moz database. A low DA score, does not mean that your website will not perform well on Google. A high DA score means that you are in the right path, but it does not guarantee that you will get better rankings or traffic, it is just a prediction.
Always try to think of the big picture, which is to create a website that over time will achieve solid rankings in Google and other search engines.