Day 16: FML. Can I have a full body transplant please?

Let me start this by listing what I ate yesterday:

Morning-Late afternoon:
Some coffee
Half a sandwich with a small glass of milk and 1 oreo
A few fritos with a little guacamole on them
Some home made punch
A mini can of ginger ale.

Dinner: 1boiled lobster (very little butter), some salad, 2 tiny dinner rolls, 1/2 ear of corn on the cob.
Dessert: 1 piece of birthday cake.

Late night snack: 2 home made s'mores (two graham crackers, two marshmellows... you get the idea.)

Now, I know that yesterday's intake wasn't small or without flaws. But do any of you think that honestly warrants a 3-4 pound weight gain?! Like, everything I lost the last 2 weeks, ruined in ONE DAY. WTF!?!?!

Additionally... 
This morning, while innocently walking down the stairs, my knee popped out of place again. Thankfully it wasn't as bad as last time, and it did go back in place. It left me laying on the stairs for a few minutes getting over the shock of it, and is now kind of achy and feeling weak... but not horribly so.

So yeah. I'm not too happy. Sometimes I seriously hate my body. Not the look of it, just the way it functions. Because, come on... that's messed up. One special occasion meal, and BAM, all progress lost and I'm back to square one. Then my knee just randomly decides to fail on me, without provocation.

I am trying not to panic or get really mad, but this is hard!! I am trying to keep my head on straight and be like "You can't change yesterday, but you can make sure you do well going forward." I'm also waiting to see if maybe this is a strange 1-2 day weight gain that will come back off.

Sigh. I guess set backs are all part of the process, but it doesn't make it any less frustrating.