Maybe. But I do feel that my plan was sound and it had worked a thousand times before. The standard BB opening is to ally Poland and beat on the Teutonic Order, expanding eastwards that way. But in my first war, the Teutons called in Bohemia and thanks to terrible AI work from Poland, I ended up having to peace out with Bohemia by ending the alliance with Poland. That was a mistake, though as Poland peaced out a month after, probably necessary.
Losing the alliance with Poland meant that they were free to launch their own wars with the Teutons later, and they got stomped all over. Twice. So I was left with a very strong Teutonic Order, allied with Bohemia and The Hansa, just sitting on my borders and routinely taking chunks out of me. That's where I went wrong, letting Poland launch their own wars and inevitably losing them.
Later on when I finally took down the Teutons, I had Sweden and Lithuania on my eastern border in a PU, as you know! That was a rather hard stop on my advance, especially as they were trusted allies. If the game was to continue in the new year, I'd probably have turned on them when you guys were launching an attack against them, but I rather fancied some PvP and I had thought Morfeo would join my side.
Expanding westwards might have a been an option, but originally I had a deal with Red to not go past the Lubeck trade node. By the time that wasn't an issue, the nations there were good allies and electors, so conquering them wouldn't have helped my HRE ambitions.