Not sure where to post this

Katie
Sorry if it's the wrong room! Feel free to flag it if need be. 
I was wondering if anyone knows why I don't get notifications when people reply to my posts. I'll get like two. Then they just stop. 
Why don't I get notifications if someone replies to a comment on my post? 
Why do I see mostly see the same 4 people responding to stuff ? I don't really follow anyone on this app. Just not into that, but why does it pretty much only show the same "Jessica 👶🏻🌞 responded to " topic ? Why don't I see if from anyone and everyone ? 
Lastly , if you follow me, does that mean you can see all my posts and what I comment even if my profile is private ? 
Again, sorry idk where else to post this or who to ask.