Accepted written job offer BUT?

So I formally accepted and signed a written job offer to my future employer last week on May 24th. Since then I have no heard back from her at all. Mind you she runs her own start up company and business...

In the job offer, my start date is on June 11th, but I’m just nervous bc I haven’t heard anything not even a background check.

I emailed her two days ago bc I thought someone was trying to reach me at her office but she replied “no we have not been calling thanks for asking” and that was it.

So is she waiting until the week I start to have everything settled?

I’m just nervous. If it’s a written offer letter, it’s a done deal right?