OK sticking my neck out here as clearly i can only relate 2nd hand as i'm a guy......
in terms of teh wand/attachment, can safely say that Mrs H has tried most of them with varying success.....although i know that umpteen folks had had differing/better results with the same ones. So as far as attachments go - it really is horses for courses. The latest one we have which for her is a winner is the flutter one.....
the internal ones just dont do it for her at all.
and as many have commented already often this type of thing can be in the mind. The minute that any goal or expectation is set makes it an ever spiraling circle of frustration. If you can break the ' i'm using this toy because i want to ....' and turn it into i'm using this toy because i enjoy.....then perhaps by lowering expectation you may get an unexpected and pleasant reward.
I encountered a woman in the past who said she rarely ever orgasmed and if so it was 1 and 'out'....it became 100% apparent that it was her head that held her back. By prolonging the build up and overall 'horniness' levels that changed quite switfly.
FWIW - sorry if stepping into areas i shoudl shut up about. Perhaps leave teh wand alone or to one side for as long as poss, take time to explore other areas than the obvious, if you have a dildo/vibe such as http://www.lovehoney.co.uk/product.cfm?p=2008 then get creative and instead of targeting teh G aim for the Deep Spot/P spot or maybe the A spot. Take a little time to notice the different sensations, and give yoruself time to build up the arousal level before switching to other vive/wand etc in more traditional areas.
have fun along the way.......