Sorry the list made you feel a bit sad but at the same time, I am also glad looking at it has made you think.
I don't suffer from HA, so it is hard for me to be empathetic about it all and it is difficult for me to understand really BUT I do understand that it is a crap disorder to have and a hard one for you to deal with as your mind will just go from one worry to another and when you are spiralling it is hard for you to get out of that spiral.
I would say, get things down on paper.... make a table of 2 columns one with your thought in it and on the other side write more balanced thoughts.... like in the first column it could be "I have stomach pains, and in the groin too I am scared I have appendicitis" and in the other challenge those thoughts and put things like "I know that I have IBS and that causes these symptoms" or "I know anxiety also has these symptoms"
sometimes it is good to have it all down on paper and challenge your thoughts... It is also really hard at the minute as it is difficult to do the normal things you would to distract yourself, but if you do get the urge to do things like take your temperature like today then distract yourself, do something completely different.. or failing that throw the thermometer away.