I'm sorry you're now having trouble after having done so well for so long. Darn.
I believe that at least 80% of your problem is the variable nature of those generic levos. The differences in binders and fillers can cause huge differences in the way the active ingredient is absorbed and used by your body. The only way to gain some semblance of stability again is to use one manufacturer's drug for at least 3 months. If it seems to be working well for you, always refill your prescription with that maker's product. I realize that can be hard for those whose health care is provided by a national health service, but that's what has been shown to work best.
You can expect all kinds of ups and downs in the way you feel until you get your thyroid hormone levels stable again. I never use the word "normal" for the symptoms associated with the stabilization process, but they are "common". Hormone fluctuation is the enemy, but you have to expect the flux until your levels are once again optimized. How long that takes is totally individual. And I'm sorry...
... I can't guarantee you'll be back to your old self in time for your vacation... but I hope