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From your explanation it doesn't seem to make any sense that you would be punished for "bathroom vanities" but you are simultaneously increasing your rank for partial exact match longtail variations of that core phrase. It's possible that they manually punished you for that phrase specifically, but that doesn't make a whole lot of sense. As long as you are growing your links focused around that core phrase in an organic fashion Google should not punish you further for this. I don't see a reason to hold off on it assuming your efforts are within Google's guidelines. I'd recommend some sort of linkbaiting scheme for "bathroom vanities" - an infographic perhaps.