Hi, my name is karenina! severe disability benefit help?

Hello, can anybody help me or have possibly been in the same situation?
its totally confusing to me and I don’t have anyone to ask and im just totally confused. Thanks..
I received pip from March 2020. I had a dependant son living with me until August 2022 who moved out aged 20 . 
During lockdown, 2020, my daughter , who was living at her boyfriends Parents house, with him, separated.
she made a claim for Universal Credit and gave my address as her care of address. She stayed here a few nights and the rest at her sisters  and dads houses, whilst following the rules of lockdown.
my question is that after I was awarded pip, I got a letter saying I could be entitled to severe disability benefit. I had never heard of it. I had been in the ESA support group for 8 years before I claimed pip as I had never heard of pip either. 
The severe disability letter said I don’t have to do anything and if I am entitled I will be notified. Never heard back so I googled it and because my son was living with me, I was not living alone, I’m not entitled.
My son was doing non advanced education and I received child tax credit for him and child benefit until his 20th birthday. He then moved away to university. Several months later I applied for help with paying the bedroom tax and they asked me if I received severe disability payments. I told them no and that I mustn’t have been entitled as I had a dependant son. They were shocked. They said I should have been getting it?
they told me to call ESA . When I called I was told that my daughter is on universal credit and lives here. This has only been her care of address, which she has always claimed and mentioned on her journal many times.Esa told me that she had to tell UC that this is her care of address again. She told universal credit about what had happened to me , the council telling me that I should be entitled to severe disability as I live alone, but nothing changed. It has been over 6 months since she told them.?