Congratulations on getting engaged! You need to relax, though - if you're stressing out this early on, you're going to drive yourself insane by your wedding day!! Have you gotten a wedding book or binder yet? If not, that is the one thing that kept me from losing my head through the entire process - it was a central place for all of my ideas, pricing information, vendor contracts and anything else I needed. My maid of honor and now-husband had matching ones, too, which made planning SO much easier. Now, it's my engagement gift to every bride-to-be I know
And maybe you didn't fall off the wagon as bad as you think - you may not have been doing it consciously, but you could have been incorporating everything you learned from while you were actively trying to lose. Or maybe it's proof that when we stop stressing over things so much, they naturally happen. Either way, it IS progress! Congratulations and hopefully, it's the motivation you need to get back in the game!