Difficulty with determining when you're actually sick

Do other hypochondriacs also have trouble seeking help when they really do have something for once? I've went to the doctor due to ridiculous fears of unlikely things like cancer, yet when I get a run of the mill UTI, I might delay treatment for days in case it's "all in my head". This can actually be dangerous in the case of infections, since delaying treatment can cause complications.

How do you determine when you actually have a problem? I'm always plagued by a feeling in the back of my head telling me it's just another one of my "episodes". I have a similar thing going on right now with LDs. I think I might have a learning disability, and a psychologist even evaluated me and confirmed that something might wrong, yet I'm afraid of asking for a referral to a neurologist (who can actually diagnose it and prescribe treatments or qualify me for accommodations at school), but I'm just full of doubt in spite of all the evidence. I think I'm just used to telling myself that there's nothing wrong due to all the false flags in my past. Ugh...