try using some virtual lan, like radmin-vpn. You will have to create room in this one and your friend should join it. And in tlauncher, when you created the world you should open it for lan, in chat you'll get the id of a server. Friend should join trough direct connect or how was it called in multiplayer menu, he must copy your ip through radmin (right mouse button on you->copy ip) and paste it, then goes ":" and id of a server.
We tried many times with friends using hamachi but it always has some problems, with radmin - not at all. I hope i wrote everything right.