Check your tools(preferences)->options->Bug Reports->View Example to find the line "Received incoming this session: true." This will confirm your router and firewall are allowing incoming connections. Also, check the "force IP" setting in Advanced->firewalls so that your public IP is used, rather than the local IP used on the (presumed) local network behind the router.

Assuming you then have enough upstream bandwidth, you should be able to run as an Ultrapeer after about an hour of uptime.