There should really be no need to stop vaginal oestrogen!!! OK then it is not due to trauma of the tissues if you've been using it for 18 months. The point is, the docs should investigate what the cause is, not just say its due to X, so stop.
That exact argument was used in my case with systemic oestrogen - 10 years ago. I had some spotting so the docs said: stop HRT and if the spotting stops or doesn't occur again, then that's the cause! So what?!!! I had an e-mail consultation with Dr Currie who said I didn't need to stop HRT pending investigation, took this back (to a different doc in the practice) and said I wasn't going to stop, but that they could investigate the cause - and thats what happens. They didn't find the cause anyway....and I'm still on HRT....
If you can I would be firm, and say you need the vaginal oestrogen, and as you have had abnormal spotting, you would like this investigated, but you are not prepared to stop due to your own vaginal health, comfort etc. There are all sorts of resons for the spotting and they need to determine if possible what is causing this. If by some remote chance you do have endometrial thickening - due to the dose you are using - then if the worst came to the worst you could take a course of progestogen to thin it down.
Please don't give up, but I realise how difficult it can be sometimes working with the medical profession, if they are not completely up to date with current thinking.
You couls always have an e-mail consultation with Dr Currie and see what she advises in this situation?
https://www.menopausematters.co.uk/contact.php (£30) - but this won't be in time for tomorrow.
Hope this helps and all the best with your appointment. Do update us on this thread and let us know what happens.
Hurdity x