Great to hear that you made it to the appointment, it sounds as if you were tempted to cancel at the last minute so fair play to you!
Sorry that the dentist you liked has left, and that you weren't told beforehand - that sounds pretty stressful.
Re. the hygienist - it's normal to see the hygienist more regularly for deep cleaning once you have been diagnosed with gum disease (even when you have perfect home care). This is because the "pockets" where the gum meets the tooth are just a little bit deeper, which makes it tricky to remove all the plaque that accumulates there at home. Seeing the hygienist regularly (for example every 3 months) will really help with preventing any further bone loss in the future.
With regards to the X-rays, that sounds right as well. Two or three years ago,
new guidance was issued in the UK for delivering better care for gum disease. This new guidance says that if someone has a certain amount of gum disease (even if it's stable and not getting worse), they should have a detailed assessment including X-rays.
The best type of X-ray for this is a panoramic one which goes around your head. Many dental practices only have the bitewing X-rays, so that's why she wants you to go to the hospital where they have the panoramic X-ray machine.
I think it's a good sign that she's doing this. Maybe she's trying to figure out whether she should refer you to a specialist for gum disease (a periodontist). She can obviously see that you're making a big effort with your home care - many people don't, so she's probably quite pleased with you and wants to give you the best care possible.
So in summary, to me, it sounds as if she's being conscientious and wanting to make sure that you keep your teeth for life. It's also good that she has prescribed an extra-strength fluoride toothpaste. The medications you're taking can cause dry mouth, which can lead to cavities - and Duraphat can help prevent this. Again, kudos to her.
So based on what you've said, overall I would say stick with her unless you really dislike her. Are the other rooms in the practice nicer? Or was that a different dental practice? If it was in the same practice, maybe you or someone you trust can have a chat with them and ask for a nicer room for future appointments. I take it they know about your autism and mental health difficulties, so hopefully they'll be accommodating.
By the way, great news that you're doing such a stellar job with the cleaning
, you must have been very pleased to hear that!!