Dominate a niche, and then add another. Keep doing that until you organically become 'generalized'.

Blog about it. Writing clarifies thought... and editing a day later will help you focus on what matters. I keep a private blog for this purpose. Keeping it private helps me not focus on the blog as a goal, but the ideas. I used to just text friends all the various thoughts I got excited about... but I learned that you gain a lot of momentum by just letting people see what you have done rather than telling them what you will do or want to do.

1. Start by researching your industry online... what types of things are websites linking to? What types of press angles are being written? And how can you do similar things?
2. Keep a list of those websites from step one... so that as you do and create interesting content, you can reach out to those people for feedback and/or requests to mention (link to) your content in the future.
3. Ask yourself which websites that your prospects spend time on... and then devise a reason those websites would WANT to link to you. After that, begin pitching them. It's a sales process like any other, so it will require some testing and amending then re-testing. But if this is your business, the job of your marketing department is to figure that out.
4. Get help from consultants as needed, to save time. Not just for marketing of course- but find people that have accomplished exact or similar goals. Investing small amounts with these people can save you months or even years of learning curves :)

The very first and last thing I do every day is read 1 page about positive attitude. It's small enough to never have an excuse for skipping, but done at those 2 critical moments... it has had a dramatic effect on setting the tone of my daily life.
My favorite book is Jeffrey Gitomer's "Little Gold Book of Yes! Attitude". It changed my attitude and my life.

1. Export a list of "other contacts" from gmail, linkedin connections, Facebook friends, Twitter followers, etc.
2. Call & email everyone (personally if possible) and ask them directly if they need your help.
3. Ask for a referral from everyone that buys.
4. Get a success story written about YOUR CUSTOMER that mentions you in as many blogs, magazines, etc that you can.
5. Write a blog with suggestions and ideas that genuinely help your prospects.
6. Figure out why other businesses related to yours would WANT to promote you to their audience. And then pitch.

Look for mentor(s) and devote all your time to learning from them.

0. You are not alone. This is a VERY common situation.
1. Screw your passion, work is a job. Find the best opportunity that you are confident can be accomplish... and do not quit until you are getting the result you want and/or until a better opportunity arises. But be careful about switching too often, the key is weigh options based on probable outcomes.
2. In my experience, it's better to offer a service that you cannot personally fulfill... because you will be forced to focus on the business itself and find/train/manage people to do the work.
3.Your primary focus should be on making sales, not operations. If you can't make sales, there's zero purpose in doing anything else. Worst case, you get better and better at selling while refunding a bunch of money until you figure out how to fulfill the orders (without you personally doing the work).
4. Just take next steps. The boring minutia that you might want to avoid, is EXACTLY the that no one wants to do (hence the opportunity); so THAT is where the value is created. Turn "off" your thinking cap during the work week, and just execute on next steps. Evenings and weekends are for planning and thinking, work week hours are for executing.
5. If this isn't working in 3 months... you either were not honest about probably outcomes when you chose the opportunity, you didn't execute during the work week, you tried to do everything yourself, or you prioritized everything else above sales.
PS. I commend you for everything you have accomplished. Getting "stuck" is super common. Most of the time, you're too much in your own head and just need to "Do the Work" as Steven Pressfield says.

A ".com" is a much better long term solution because Google and people generally recognize that as more authoritative/ trustworthy. The best way to change a ".co" over to a ".com", is by creating a "301 redirect" for EACH PAGE and keep everything else the exact same until Google indexes the new version. Also, you might want to contact any important inbound links and ask them to update their link to be to the new address. And you can register both domains inside Google Search Console and submit a "change of address".
Does this help?

Ask your customers :)

#1. Decide to invest just enough time to solve your specific goal and then move on to the next goal. DO NOT LEARN JUST TO LEARN (that's a hobby, not a business)
#2. Read Google's Guide on SEO https://support.google.com/webmasters/answer/7451184?hl=en
#3. Read this short article, it's the BEST SEO ARTICLE I HAVE EVER READ https://moz.com/blog/every-site-is-linkbait-linkerati-worthy
#4. Publish content that webmasters will WANT to link to (ie. it's genuinely useful for THEIR audience which ideally is YOUR audience as well)
#5. GET LINKS THAT WILL SEND YOU LEADS if you sell anything by picking up the phone and calling people or reaching out proactively somehow just as if it were sales itself you are doing.
#6. Choose keywords your prospects are using by looking at the Google's Keyword tool, and start out with longer tail phrases until you start noticing that you can rank for harder and harder ones
#7. Did I mention to avoid learning for the sake of learning? It's a black hole that will suck your life up with no return. Just learn what you need to know to solve the next problem directly in front of you and then move on :)