Wirelessany1 assums that most Plaintiffs are law-abiding citizens and will follow the proper procedures. While most ARE, sometimes a Plaintiff may SAY they have served you and not do so at all, hoping to have an advantage at the trial.
You could call the court clerk and ask, or in some jurisdictions, they have online access to check current court records. (Beware, if you're searching by a name, you might be charged online for the inquiry).
(Btw - those Attorneys that have contacted you should have a case # that will surely assist in your inquiry.)