I know how to build, but I don't know how to promote

I'm a tech person and it's not a problem for me to promote my products or whatever I build. Today I realized that I don't know how to do it. I want to do it and have the will to do it, but I don't know how.

Money is the obvious way to promote something, but I don't want to throw my money just like that. Let me give you 2 examples.

Project #1
It's a gay dating project. With a particular purpose and problem to solve. I've been interacting with people on Twitter for months and I even got 5k followers in about 5 months.
I'm commenting on related posts on daily basis, my every pic has a watermark, and I post every 2nd day regularly. I also write blog, very specific to that niche. I write at least 3-4 times per week.

It's been around 5 months and not much has happened. I got maybe around 80 users. Since it is a geo-based app, it's not really effective. I know that I need to target people in a specific area for it to make sense.

Project #2
It's for youth and doesn't have a specific niche. I think TikTok audience would be good for it.

I started TikTok account, but I cannot just post anything, I have to post something related to the app. I have to create content that will represent the app.

The bottom line is, I'm trying, and I want to do it, but I feel like I'm doing the wrong thing. I feel like I don't know what to do and how to do it. I'm not expecting results right away, I just want to be sure that I'm doing the right thing.

It's like non-tech person is trying to build something. You can do it, but you are not sure whether what you do is correct and is the right path to go.