it sounds like you really care about your therapist and are genuinely concerned about whether she his okay. your fear that you will 'contaminate' her sounds very real, even if concretizing that with respect to AIDS is maybe problematic...

> I just have all these ways it can happen and it's just that no one realises it.

when you feel like that... are you able to try and think a bit about what you might try and say to another person if they thought that you could get diabetes from stepping on cracks or parkinsons from not washing your hands 100 times a day, or contract OCD by talking to a person with OCD? even if they said that they 'just knew' because they had this special feeling or that they saw or heard it on tv it would be more likely that the message they had received was in error than that it gave them special insight that all the microbiological and epidemiological data had simply missed...

your feelings and fears (in the first paragraph) seem very real... nothing in science is known 100% but i'd say that contracting HIV from a doorhandle would be about as likely as those other scenarios that I mentioned in the second paragraph. So... really not very likely at all. seems to go against everything we know with respect to transmission. with respect to the increase in prevalence maybe you are underestimating the prevalence of prostitution, needle junkies, and the number of infected women who go on to infect their kids either in the womb or via breastfeeding.

> I always tell my psychologist to be careful and I try to help, because I'd feel really guilty if something happened and I didn't say anything. Now I think it has happened and it's my fault.

that must be a really hard fear to live with...