It could be either or both, actually. One week in the bottle is not very long, so it may not be fully carbed up yet which would explain the watery taste. Let them sit for 2 more weeks and then try another one; it should be better.
If you post your recipe and process, we might be able to help determine if that is also at fault.
Primary/Secondary: #133 Scottish 80/-
Kegged: #132 American Wheat
Planned: IPA, Brown, Pale Ale