Port Forwarding help using NAT

[slurpee7]

Hello,
I am a newbie to Virtualbox. I have a guest virtualbox running Windows server 2008 r2 and its running through NAT. I am running SharePoint on it and I'm trying to get to it through port 80 internally/port 8899 externally. I ran VBoxManage modifyvm "VM name" --natpf1 "sharepoint,tcp,,8899,,80" and opened up the ports on my firewall. However, I still can't get to it. I'm using https://www.dyndns.com/support/tools/openport.html to test the connection.
My external IP is: removed
Internal Host IP: 192.168.2.x
VM Ipconfig IP is: 10.0.2.15
IP if i test from inside VM at http://www.whatismyip.com: removed

The guest is running DHCP and is connected to my corporate work domain via VPN from the host.

Is there a better way to do this that would actually work? Any help would be grateful!

[Sasquatch]

I removed your public IPs. Don't want to invite unwanted guests.

Why use the elaborate way of the CLI when you can use the Port Forwarding button in the GUI? Much more fool proof. Then to test it, use your browser and go to http://localhost:8899 to see if it works. When that works, all hands are off of VB and you're on your own to fix the redirect from the internet to your Host.