Happy almost diaversary!
I hope the advice you're being given is better than what I had! I only listened to their fixed dosing advice for a few months as it was so vague they'd just say 'have a couple more potatoes' but I often didn't have the appetite and have never liked having the same meals day in day out, which is what they were trying to get me to do. I heard about carb counting online and asked them about it and they said 'oh yeah, we used to teach it but people found it too hard so stopped'. They were more than happy to support me through it after I'd asked though.
My point being, perhaps if you email/ring and say you were due to have an appointment and wanted to discuss carb counting they might be able to offer email/phone/skype etc support?
In the mean time, maybe subbing a usual meal for say low carb main (salad/fish/meat etc) and a slice of cake would still allow some freedom for you to mark your diaversary and not feel too restricted in how you can celebrate? If you're concerned perhaps doing this at lunchtime would still give you the rest of the day to observe your blood glucose rather than worrying about low/high overnight?
Do what you feel comfortable with, hope you enjoy though!