'the walls look green but it's more of a gray'.

well, which one? have you tried putting in cooler temperature light bulbs? that will make a diff. you didn't say what color vanity top youre getting, but the shower curtain looks good w/what you have.

It’s this color gray Revere Pewter

The vanity top is white with small specks of gray.

Yes, it all works well together, you did a good job.

Does the curtain seems to be too much

patty-

Since you asked, I'll say my reaction was that is a rather strong statement in a bathroom, particularly if it is not a big bathroom. Personally, I would go with something lighter and simpler to open the bathroom up. It's not that the curtain is unattractive, but it's just dramatic and I would tire of it. My last observation is to ask if lighting in the shower is adequate, given that the curtain will not let in much light.