After a year and a half, my new niche website still doesn't rank for all but one keyword

I developed a website focused on a specific standardized test, similar to the ACT but different. I wrote around 20 articles targeting various keywords related to the test. After a year, only one of my pages ranks in the top 10 for a keyword. Some key points to note include:
  • The website is one year old
  • The quality of my articles is comparable to competitors
  • I have only one paid backlink
  • According to Ahref’s, many keywords have KD’s of 2 to 12
  • My website has a domain rating of 1
  • All pages are optimized for mobile, speed, proper h1 tags, etc.
  • The keyword I rank for is not covered by competitors in the same niche

Despite these efforts, I am struggling with my low domain rating and unsure of how to improve it after a year and a half.

Building more links is crucial for improving your domain rating. Since you only have one paid backlink, focusing on acquiring more backlinks from relevant, high-quality websites can significantly boost your domain authority.