I think possibly what you would like to hear is that you don't have to stop seeing your T and that you can work through these feelings. And actually, I would say exactly that :-)
So let me tell you why:

1. "Recently, I made quite a big breakthrough in terms of my life/ way of thinking"
2. "My T was wonderfully tactful and sensitive towards my feelings, and I don't feel weird going into session"
3. " At the moment having appointments with her is a really positive thing and the fact I can't be with her romantically isn't significantly painful as such - it's just irritating"
4. "Even if I worked out that it isn't really erotic love, and it's just maternal transference..."

This is what screams louder than than:
" but I've read so many accounts here where the love feelings deepen and deepen and cause untold pain."

I think what you're feeling is quite normal. You are not particularly distressed by it you are distressed at the possibility that it WILL become distressing.
But what if it won't? What if this is what you need right now to work through some things? It sounds you had some good sessions lately and I am so glad to read that because you had a tumultuous time not so long ago. This might be a great time to accept what you're feeling and tackle it.
It doesn't have to be masochistic, not everyone who has (romantic) feelings for their therapist is suffering tremendously. Many use it to work through the issues that cause this in the first place and find freedom. You can do it too. You are doing everything right, you are putting yourself out there, even if it doesn't feel like it's working for you (yet). But I really strongly believe you are at a better place in your therapy than maybe ever before (as far as I can say that from what I have read) and this could really be the road to many more breakthroughs.
Enjoy the love you feel for your therapist, enjoy how it makes you feel and the anticipation to see her etc..
As long as you don't start to be masochistic with yourself and deny yourself the chance to work through this, I think this can be good, even though you might find it difficult to see.

Much love,
Amelia