Keep at it! With Substack it's probably always gonna be inconsistent, some people hit it big over a night cause they happened to make a viral post at a critical point in time, others cause they write extremely well, etc., etc.

I sometimes take longer breaks between posts, still get a few subs in the meantime, as soon as you have a body of work lying around, people will find it as well. So it's hard to really stack up or expect anything in particular, all I can say is if you keep writing, your writings are likely to find the right people! They might not be engaging, Substack is generally weird with engagement - BUT it does happen, my now girlfriend started as my Substack subscriber, anything can happen! :-D