I'm having trouble forwarding a port through PfSense
PF WAN: 192.168.254.203
PF LAN: 10.0.0.1
Try removing the first WAN rule you have (allowing SSH to the WAN address). You should only need the rule allowing SSH to 10.0.0.6 and the NAT port forwarding rule to forward to 10.0.0.6
Also, best practice if you're actually using this for SSH would be to limit the protocol on those rules to TCP, which is what SSH uses.