First of all, do NOT make your sites public on the biggest SEO forum on the planet. There are many reasons for which you should not do this, but I won't get into them because I've explained them several times already. Just know that it's bad and that you should always keep your sites and keywords to yourself only.
So, first things first, report your own post and ask a moderator nicely to delete your site...
Secondly, DA is a useless metric most of the time, and it's definitely useless when it's low. When it's high (over 80 I would say) it's a bit revealing, but when it's as low as yours it's meaningless, so you shouldn't bother with it. DA and (real) authority are 2 different things, albeit high DA can be a cause of authority.
So, the second thing is: do not concern yourself with increasing the DA, if your site is good you can outrank stronger sites than yours even if your DA is low.
And lastly, to answer your question about improving authority, I will say this: you can improve authority in 3 ways, either separately, or cumulatively with each other:
1. get traffic... LOTS of traffic. Get so much traffic that google has no other option but to rank you because you are too popular, and this popularity is what will make your site authoritative
2. get backlinks.... LOTS of backlinks, but preferably good backlinks. If you get 1 million bad links your authority will not increase (and it might even harm your site in some cases). But if you get lots of good backlinks your site's authority will increase for sure.
Good backlinks = backlinks that meet any, or all of these conditions:
a) come from good sites (good sites = sites that are trusted by google and which have good amounts of traffic from google and other trusted sites like reddit, for example)
b) have authority themselves (usually niche edits have authority, but if you can't get / don't want to get niche edits you can also get good PBN links, good guest posting links, and good edu / gov links. All of these links can boost your site's authority for sure)
When I say that the links should have authority themselves I'm referring to the fact that the links should come from pages that either have good UR / PA, or have quality organic and / or referral traffic, or both.
c) are d0follow and are indexed... if they're not d0follow they don't pass link juice (authority), and if they're not indexed they don't pass enough link juice (authority)
3. get topical authority (looking at your site you seem to have on-site topical authority, but I didn't check off-site topical authority, which basically means backlinks from the same topic / niche as your site, so if you don't have enough such links make sure to get them so you can create more topical authority)
That's how you improve your site's authority.
Also, why is everyone linking to the same page lately? What is wrong with you, people? Linking pages to themselves doesn't make sense and it doesn't help you in any way (at least I've not heard of it). So, why are you doing it? You're like the 3rd or 4th person that I've seen in the last month to do this, and I honestly don't understand why you do this
