If you have anxiety, leave self-promotion aside, instead try to go in this order:
Answer every comment in your work.
Even if it's just an emoji comment, try to reply with some words/emojis back, even a "Thank you " makes a huge difference. It encourages people to comment again, which makes them engage more with the story.
Check on others comics
Look for people on your genre with the same amount of subs or less.
Read their work.
Sub, like and comment the work. You can start with something simple like: "Wow, great work! O.O" or "Love this page, keep going! ". It seems like nothing, but everyone welcomes a bit of appreciation, and if they have same or less subs, there's more chances they don't get many comments, so they'll see yours and even check on your stuff.
BONUS TIP: To know if it's really worth it to interact with a certain author, you can check on their profile: if they're subbed to other's stuff (unless they have a hidden library), specially if they're subbed to small works, and if they comment out of their work (because it means they reach out and interact with other people).
I've worked in this two points for about six months on Tapas and Smackjeeves (back when it was community-friendly). Once I saw I was doing it almost automatically, I ventured into Instagram. The rules are the same with a smal tweek:
Comment and like without following unless the person does the same back.
You check on their work.
Like the hell out of it.
Comment about it. You can start with just "Great work you have here O.O". Try it to be a sentence of at least four words.
Move on to the next profile.
I say this because it takes more to analyse someone's behaviour on IG. You can check their counters, if they reply to comments in their posts, when was the last time they posted something... But it's a lot of things and it's faster to "smell the flowers without stop walking", to say it that way.
In big places is better treat your following as a small curated group of artists that you steadily support, because they also support you back (And clean and dump regularly those that stopped interacting with your stuff despite you keep interacting with theirs).
This is the best self-promotion you can do, show interest about others work and about your readers appreciation. It's how the word of mouth works digitally and it'll bring you more joy than placing ads "Read my comic". Give before ask
BONUS: To trigger comments on your stuff, comment something on the author note, make questions, say thank you for the interest, tell them about your artist life, about something remarkable that happened while doing that page, etc. Demonstrate there's a person behind the comic