That's good - if the firewall icon's disappeared then it sounds like you port forwarded successfully

Try changing ports. There's no guarantee that this will help (since your slow speeds are probably due to BT) but it's worth a try. In LW go tools > options > advanced > firewall. Change LW's listening port to 65000 (or you can try any ports in the range of 49152 - 65535) > apply > ok.

Once you've done that, you'll need to set up port forwarding for that new port number. No need to do another static IP setup, just use the same static IP address that you used for port forwarding before. LW's listening port, port in the 'manual port forward box' & port forwarded within the HomeHub's setup must all be the same number.

Have you tried connecting outside of peak hours? You might find that you're only being throttled during BT's peak hours (check out the 'traffic shaping & port throttling' section in the link below for more info.
BT Total Broadband - Wikipedia, the free encyclopedia