I think trimming your piece to fit is fine, there's nothing wrong with that. Just make sure you don't accidentally cut off hair that you intended to be part of your piece.

Also, depending on how the lace looks on your head, sometimes a lighter shade under the hair is more realistic because our scalp is covered by hair, and doesn't tan. It would be nice if we could see pics of the lace on your head.

Also, yes let your hair grow up, that ring all around your head wil blend away once your real hair is longer.

Don't give up!

Leamon