This quick powershell script against your profileUnity security group will tell you how many members are a part of this group. This also includes nested groups. It will also remove any computer objects or disabled accounts from the final count as well.

Run as admin

import-module ActiveDirectory
$membercount=Get-ADGroupMember -recursive “YOURADGroup” | Where {$_.ObjectClass -eq “user”} | get-aduser | Where {$_.Enabled -eq $true}
$membercount.count