Hi Collis, this is a very common issue; struggling to grow the audience to your podcast, posting on all the right platforms and messaging all your friends and family, but after an initial bump of listeners, your growth flatlined.
Try following a Value First engagement strategy. We've used this to great effect (we're now a top 0.5% podcast with 20,000 monthly downloads and growing) and our clients have seen it double their audience on a month-by-month basis). Here's a summary of what that looks like:
1) assuming you have defined your ideal listener and their niche (an important step that you really can't miss) you need to find the groups they are in, the newsletters they subscribe to, the blogs they read, and the podcasts they listen to.
2) join the groups (I'll come back to this in a second)
3) reach out to the hosts/owners of the blogs, podcasts, newsletters, etc, and pitch them on your guest appearing or writing on their platform; using keyword searching or something more sophisticated (Answer The Public for example) come up with a few specific questions that you can provide expertise on where you're adding value, or making a difference to your listeners. Your podcast may be more on the entertainment side, so think about who you are entertaining - who are your kind of people, what other podcasts/blogs (etc) are they engaged with, and what value you could bring to those hosts. Believe me, as a podcast host who relies on guests, I'm always looking for people who will add value to my audience, so anyone who reaches out to me who can provide it will get on my show and get exposure to my audience.
4) on the FB groups, you can add plenty of value without breaking the "no pitching" rules. Join the groups and then become active. Answer questions, participate in discussions, and post engaging content... Assuming your banner is optimized and trumpeting your podcast with links, clips, reels etc, people will find your show. It's the know/like/trust factor.
The one challenge is that it takes time. I've recommended at least 20 minutes per day and not to expect results for at least one month. Remember: you are asking for cross-platform behavior which is inconvenient. People listen to podcasts at different parts of their daily lives than when they're scrolling through their social media. But - if you do enough of it, enough people will seek you out, see the link to your podcast and then click on it and hit the subscribe button - even just to bookmark it for later. And that's your listener number up by one. Oh, and it's evergreen because people will search for information or see something you posted days - or even months or years - later, so this really can be the gift that keeps on giving.