[sigmar]

>only 1 - 2 times a month

I have suspected that facebook punishes your visibility if you don't post frequently (like a few times a day). Have you tried posting much more often than two times a month? Try two a day and see if your average engagement increases.

[gnicholas]

I've found the opposite — posting frequently results in decreased visibility in my experience. My wife and I trade off posting family photos of our kid, and whenever one of us has recently posted the photo gets much less of a reaction (i.e., 25 likes instead of 65).

[quantumwannabe]

I've also found the opposite: Facebook sends me notifications to check out a friend's post if they make a post after not posting for a while.