Hi there.
I think what you're experiencing during sex is largely a product of the tension...though I do believe the mental "preference" may be a significant factor. That, I think, can be worked out in time. I would imagine you would simply need time to "reajust" to it, so to speak. You might want to speak to her about it as well...explain that you're used to this, and you want to have the ability to be satisfied without your fetish. Perhaps you and her could "ween" yourself down to a point where you could climax without it?
As far as the sex itself, could you two work on finding another position that works? That, I think, is the best way to remedy that. I would confess I'm not overly knowledgeable on the subject, but perhaps the internet could yield a few answers specific to your question?
I hate that I can't offer more specifics, but I do think your problem can certainly be remedied. It's just a matter of communication.

My best to the both of you, and good luck!
My best,
Harley