If your application was as thin on details as this post, I'm not surprised. Why don't you lay everything out, what passport you hold, what scheme you tried to enter on, where you applied, what documents
you supplied, how long were your financials were in place, what type of account were the funds in, were further documents requested? etc etc.
Passport control stamping out doesn't do anything in regards to 90-day reports. If you need immigration services in the future a sharp-eyed officer might notice that you missed your report and fine you, or not. You can report in person from 14 days before till 7 days after the 90 days due date.
I wouldn't worry about it. If they don't like the picture they will request a different one. More than likely the message was just a standard reminder of acceptable positioning.
Lots of pertinent details can be gleaned from posts that aren't anonymous by checking a user's FB profile and past group post history. If they want real privacy they can lock their profile.
No reputable clinic, hospital, or doctor is going to provide paperwork without seeing you in person for diagnosis, treatment plan, medication, and ongoing care appointments.