Site will not seem to rank

I have a pretty new site - domain is 4 months old and site is 2 months - that, will not rank for some fairly general terms such as "software for <type of business>" where the type of business is a fairly niche business. I have done some SEO and getting sites to rank before and it normally took about a month to start getting a slow trickle of traffic. So far I've focused on, on-page SEO (meta description, keywords, page structure, etc) and have written a bunch of content for the site (6 blog posts with 2 public so far and 4 scheduled), submitted the website to google for indexing, added to company social media accounts (increase chance of google finding it) and tried to drive traffic via sharing the site within some groups I am in to drive initial traffic (this worked but zero since sharing so was only a burst). The one thing I have not managed to figure out a good solution for is getting backlinks. I know that directories used to work but have heard they can be seen as spammy now so I've avoided them mostly. I've submitted to a few that are niche related and something someone would go to to compare software or the generic ones like G2. I am working on a few pieces of content to go try to get some links via a guest post. I do also have a small list of sites that list direct competitors or general ones that I'm going to reach out to about getting added to their list of companies in a comparison. What am I missing on getting the site to rank for at least 1 keyword and start driving some traffic?