You need to use the Where argument to tell the report to print only the
current record.  Since I don't know the names of your table fields or form
controls, I will use the following as examples.  You will need to change the
name to yours.

DoCmd.OpenReport "MyReportName", acNormal, , "[AUTO_NUMBER_FIELD] = " &
Me.txtAutoNumber

MyReportName = The name of your report.
acNormal means go straight to the printer
[AUTO_NUMBER_FIELD] = the field in your table that is the primary key
txtAutoNumber = the control on your form that is the primary key of the
record you want to print.

Now, there is one other thing to consider.  If this is a brand new record
you have just entered, the report will not find it because it is not yet in
the table.  It is only in the form's recordset.  To get it into the table,
you will need requery the form.  The problem here is that whenever you do a
form requery, the recordset goes back to the first record in the recordset,
so you need to reposition your form to the record you were on.  Here is some
"air" code to do that.

If Me.NewRecord then
   lngKeyValue = Me.txtAutoNumber
   Me.Requery
   set rst = Me.RecordsetClone
   rst.FindFirst "[AUTO_NUMBER_FIELD] = " & lngKeyValue
   Me.BookMark = rst.Bookmark
   set rst = Nothing
End If

Did the DoCmds you tried include these?...
 DoCmd.RunCommand acCmdSaveRecord
 DoCmd.OpenReport "YourReport", , , "AutonumberField=" & Me.AutonumberField