Does this mean I have been hacked?

Hi everybody...

I am hoping I can get some direction.

I built a site last year, its a sales page and my own ebook.

I really started promoting it, and the organic search traffic went
up like crazy. I have backlinks to the site, and other sites pointing to it.

So in January I had 64 unique visitors...and 2-3 sales
Feb 127 uniques and 5 sales
mar 137 unique and 5 sale
April 145 uniques and 10 sales
May 200 uniques and NO Sales!

I am on page one #1 for three search terms out of 500K to over a million competing sites
I am on page one #3 for three search terms of the same number of competing sites

Already in June for 2 days I have 22 unique visitors...and the hits are huge...but they could be spiders and bots...so I don't count those...I am going by uniques.

It's a book about starting an offline business, so it's not seasonal.

I had a friend buy the book to make sure all systems are working.

What would cause me to go from steady sales to the most traffic yet...and no sales?

One other tidbit...I am not on the most current version of wordpress..it's one version behind and needs to be updated. I know this can leave the site vulnerable...I just found out. But I don't know how to upgrade the site.

The last thing I want to do is mess up my rankings

I use ejunkie for my download...

Is there a way that my link could be stolen? I don't know how to check...

Any advice or thoughts would be so appreciated.