Sometimes you just have to keep living and learning and gathering experiences and gaining the kind of perspective that only time can give you. Therapy helps but so does plain old growing up. It sounds to me like you're overthinking this, mapping out the pitfalls of every possible course of action.

Whatever you do is going to involve messiness and pain and mistakes. You just can't avoid all pain. But you'll learn from all of it and it will almost certainly get easier. Having seen and experienced stuff before makes it all a little less raw and a little less overwhelming the next time around.

I say this without condescension--just offering you the benefit of experience. The really intense maternal transference will only likely affect your real life relationships temporarily. It won't supplant all your healthy friendships and romantic relationships long term.

I think you really got to the core of the issue when you identified that what you most need is someone to care about you and be with you as you sift through all this painful stuff. If you haven't yet, you'll find that therapist, she's out there for you! With that clarity of purpose I think you'll probably get what you need from your therapy experiences. Living, working, and participating in the world will help you where therapy can't.

(Also I second what Leah said about how sometimes it takes a while to find the right T. I've seen over 20 therapists and psychiatrists in my life (some just once though) and only a few of them stand out as having been really great.)