Quite true there yes.
I'm not trying to bring you down here, but 10k reach is still a bit low for your numbers. You should be hitting at least 30k, but you've mentioned it being a personal acc, so I'll hold off there.
1 - 2/month? So like are both these post shoutouts? Now this makes sense - You need to post more bud.
This goes in hand with the fact that you don't post much. When you stop fllw/unfllw , yes maybe it will trickle down a bit, but if you're posting solid content regularly that your followers will like to see, then it should be ok.
That last part about engagement dropping isn't necessarily true. Really not about explaining the algo + math involved but to simply put it:
Your EG per photo may drop a bit, but the overall total will increase once you start to post more. If done right, your reach will certainly increase and hence, your EG.
http://www.socialmediatoday.com/social-networks/inside-instagram-algorithm
Would recommended a minimum of 1 post per day, but maybe you can make it with every other day.
Did you follow the right procedure in checking to see if you're shadow banned? Are you checking this from your own account?
Someone recently posted about this
https://www.blackhatworld.com/seo/solution-to-ghost-block-problem.928616/#post-9910344
