Motivation to get back after falling off the wagon for two days?

First of all realize the difference between an increase in weigh caused by temporary water weight and food in transit vs a weight increase caused by an increase in fat stores.

And then realize that baby feline poo poo happens and that nobody's going to be perfect a hundred percent of the time nor should they be and that your long-term consistent activities are what will determine your weight level.

So stop guilting and start doing your normal eating plan.

And yes your eating plan probably needs to, in the near future, start being more accommodating towards eating "certain" foods in some sort of moderation.

But.as mentioned, as of the next time you open up your mouth to eat or drink you resume your previous eating plan!

I think there's even a big brand commercial about just doing that

Btw, keeping to a long-term sustainable deficit level also helps with adherence. 2 pounds a weak and 1200 is not suitable for everybody <-- just throwing that out there "in case"

You would have to eat 51,450 kilojoules above your maintenance kilojoule limit to gain 3.5 kg in fat in that time.

Didn't happen.

You gained poo, and your body held onto more water than usual from the increased salt and carbohydrates. Nothing to worry about!!

When losing weight, it's good to have occasional days where you eat more. When you get to maintaining your goal weight, you have to be over your limit some days if you're over your limit other days. This was just good practice.

Think long-term. Is your way of losing weight letting you eat the things you love in moderation? The sooner you learn that, the better your prospects for keeping at a healthy weight for life.

1. What wagon?

2. 1kg fat = 7700cal. This is how much you need to eat above maintanance to gain 1kg. So 3.5kg = 27000cal. That must've been some binge! That is 60 whole chocolates or 16 jars of 300gr Nutella! And this is on top of the other normal meals.

3. Weight loss takes many months and for most of us - years. Do you expect to stay on a deficit e v e r y single day for a year? Noone does that. Noone.

4. Your weight includes tissues and water. Humams are made mostly of water and its amount in the body varies constantly ro serve the different functions. So does your weight. Losing weight from one day to the next does not mean losing fat necesserily. Gaining weight from one day to the next does not mean gaining fat necesserily. In most cases it is the water that varies and thus your day to day weight on the scale is irrelevant. Download a weight trending app.

5. Chill. It won't work only if you decide not to do it. But why would you?

Log EVERYTHING.
Don't JUST weigh (with a scale is best) everything you eat, also write why you are eating it (i.e, lunchtime, hungry, kind of bored, out with friends, watching tv) and how you are feeling right before, right after and an hour after (hungry, comfortable, normal, full, very full bloated, drowsy, OMG I am so damn sick of this crap I want to throw the whole plate out a window, etc).
This gives you a baseline pattern for your normal habits and routine. From there, it's just a matter of experimenting. Are you very full after dinner? Cut back on a few things. Does lunch leave you bloated and gassy after an hour, try less or no mayo, and see if there's something you don't mind dropping each meal (fries, or cheese, or maybe only 2 tacos instead of 3).Are you starving an hour after dinner?Maybe more fats during.
It's amazing how quickly these small and easily sustainable changes will add up to big calorie cuts. Only cut one or two things at a time, until they become habit instead if trying to do everything at once. That way they become individual habits instead of one big "diet".
Break things down into individual behaviors and habits. Instead of looking at this as an all at once, or all or nothing proposition, find ways to break things down into smaller and more sustainable habits. That makes it much easier to pinpoint where something is not working, and fix it, rather than staring at the whole jumbled mess of NOT WORKING. Plus, when you do backslide, you are less likely to drop everything, just one or two habits, that can then be fixed again. Otherwise, trying to everything at once, means that you are likely to leave out something important (like weighing food), and pay excessive attention to things that aren't. (Like fiber drinks and vinegar)
Don't demonize foods that don't actually make you feel bad. Obviously if you have food sensitivities avoid those things, but don't cut out all your favorite goodies because they are not "healthy". Think of your calories as a type of currency. You should purchase the nutrient rich stuff first, budget for regular treats, and don't waste any calories on stuff you hate, even if it is theoretically good for you.