Administration Processing after approve visa

[Amaning]

Hello everyone, My name is Amaning and I'm from Ghana. My wife is lawful permanent resident in the US. She filed for me and the priority date is March 18, 2013. We've gone through all the processes at the NVC. I received a mail from the NVC saying that they've finished processing my application for the visa and have sent all the require documents to my respective consular section in my home country; that is Accra Ghana. They will mail me when an appointment day is ready. My wife n I received a new email in a month time stating that I have a visa appointment on May 22, 2014. so I have to do the medicalls prior to my interview date. I went for the interview on the 22 and I was asked to come again on June 24, 2014 with further documents to prove my relationship with my wife. They gave me 221g form which talks about that document. I gathered all my necessary document and went on the 24 and after the interview with the consular, she requested for my passport and picked the collection form whiles she was typing, she stopped at point in time called for another staff member so they asked me to wait for couple of minutes. She called me again and she gave me my passport plus a form. She explained to me that my priority date that March 18, 2013 is not reacheable and they are currently working on May 1, 2012. That I should keep the form and keep on checking their website when my priority date is due and come with the form on any wednesday so that they will schedulled me a visa interview with a consular. she added that i shouldnt do anything again but to wait for the priority date to become due. We are confused!! My problem is, the medicalls that I did will last for six months and my police clearance too will expire in December so does mean that I will do it again if my priority date is due after the expiration of the documents. Please help me!!