Firstly, you can fit the Estring yourself, I do - you don't need the GP to fit it!!! It just slips in and you may be aware of it for the first day or two but after that it's fine. If you ever used a tampon then you can use the Estring.
If you used Vagifem 25mg then had to change to the 10mg dose, this might explain why your problems increased - if you hadn't used any Vagifem then your condition may have been even worse by now. Maybe you needed the 25mg dose?
VA emerges in different ways with different women. All post menopausal women will have VA but for some it isn't troublesome(maybe just dryness) whilst others get pain, infections, bladder issues and terrible burning. As you are post meno I suspect VA will be a contributing factor to your issues.
I'm not entirely sure what the dosage is with Estring but it makes sense to me that it's slow constant release will bring more benefits than twice weekly ultra low Vagifem.
If I were you I'd give the Estring a go - it's unlikely to cause any problems but it may do some good. You can always take it out if you don't like it.
I hope that helps DG x