I am no expert either but the signs you describe don't sound at all like the things my mum (who has vascular dementia) has been doing. It started off with her not being able to remember the right word for things, quite straightforward things like shoes for example. She'd say where are my... my... and could not think of hte right word.
It does sound a bit like OCD to me and worth exploring I think.
It is totally natural to worry. When my mum got a breast tumour I had a pain in my breast and had to go for a mammogram to set my mind at rest!
Good luck x