I'm glad all is well Lynanne! Fixed at the brim usually means your baby's head is just resting at the top of your pelvis, so almost ready to engage. And 36 sounds great! That's only a week out, and up two two either way is totally normal. Although I totally ignore measurements as I'm measuring 47, yet no extra fluid and baby is only a little in the larger side. I just carry big. I don't know why they bother measuring me anymore. Seems a waste of time.
Don't worry about being paranoid either. I'm totally the same at the mo. Every twinge sends me running to the bathroom. Had my results today though and it's viral tonsillitis so today is my last day of having to worry. If I go into labour from tomorrow then all will be fine. My throat bloody hurts though.