how to help my sister with OCD who's refusing to go to therapy but venting to me instead

hi all, hope you're doing well :)

i spend almost all my time with my older sister, and though she isnt diagnosed we're both 99% sure she has OCD.

her main compulsions are health related, such as thinking she's having a stroke or heart attack, worried about injuries giving her sepsis, etc. she has an anxiety attack nearly every day about it.

most of the time i will end up looking up symptoms for her, since if she searches herself, she believes she has whatever fatal condition it shows her.

i care about her very deeply and i am not shaming her at all, i completely understand how difficult it is to live like this. the thing is, it's been over 2 years now and it's wearing me down.

i've been telling her for around 3 months now that she should talk to a therapist, but she keeps finding reasons not to, whether it be time, money (we looked up prices and know she can afford it), or the belief that it simply won't help.

what do i do in this situation? it's hard for me to not get frustrated, so she's started being aggressive and keeps insisting her intrusive thoughts are true unless i find concrete evidence for her exact problem (i.e. today her finger was hot and painful at the tip after a minor cut, and since i couldn't find someone else with the same symptom she's convinced she's gonna get sepsis)

sorry this is long, i hugely appreciate any advice!