Why haven't I heard from ESA?

I have been on ESA for at least ten years. Originally I was on contributions based, in WRAG after two truly horrendous medicals (I was asked why I haven't killed myself yet) but I was never asked to participate in any WRA. Then the law changed that you could only get it for one year (contributions based). However, as they were still paying my NI stamp, I still had to reapply at the end of the next year. So I did. Then very much to my surprise, ( and relief) I got a letter to say that I was now in the support group, without a medical. That was about 6 years ago and I haven't heard anything from them since.
I have had to change over from DLA to PIP two years ago. Is it likely that they have used my application for that to reassess me for ESA? My PIP application was quite grim and there was evidence of quite severe and ongoing MH problems.
Obviously I don't want to go through the trauma of reapplying but I am sure it will happen one day. My friend on the other hand has had to reapply every year and she is in the support group too.

Going back to March 2015, I had my last ESA assessment.

As I'd heard nothing from them, I think it was January this year, I gave them a call. The call handler said I was due to be contacted on the 17th of December 2019.

I don't know if this is relevant, or that I've been assessed without been contacted.

The girl I spoke to on the phone did say something about the 'nurse had decided this'. I just dismissed this as her just waffling.

I'd be interested to hear if anyone else had had any similar kind of experience?

Sorry if this is in the wrong place but I can't find my original thread re this which I did post around the time.