Maintaining??

I can’t really answer your question. I set my daily calorie limit at the beginning, past it, and kept losing weight until I just didn’t lose anymore. So, I’m still using my original calorie limit, lost 25 lbs and have been maintaining for a month so far. The slope of my loss curve became very low towards the end.
What I’ve heard other people suggest is to add 100 cal when you hit your goal weight and see what happens… if you continue to lose, add another 100, etc

It depends on what you mean.

If you've been using MFP's calorie estimate and losing weight exactly as expected, then you can change your MFP goal to maintenance and expect to maintain as expected. Some people find that they maintain for a while, then start slowly losing again. I won't go into why that can happen, but it's moderately common, but not universal.

If you were losing faster or slower than MFP predicted, you'd get the same relative effect if you just switch to what MFP estimates as your maintenance. If you've lost faster than expected, you'd likely keep losing at "maintenance" calories. If you've lost slower, you'd probably slowly gain.

Before I forget, there's a whole discussion here about how to estimate maintenance calories and some chat about alternatives for getting there, in this thread:

https://community.myfitnesspal.com/en/discussion/10638211/how-to-find-your-maintenance-calorie-level/p1

I can understand feeling anxious, but keep in mind that it's very unlikely that anything dramatically bad will happen. If you overshoot your maintenance calories by 100 calories per day, it'll take over a month for you to gain a pound of fat, and probably longer to notice amongst routine water retention fluctuations. You know how to lose a pound, right? So why stress over the possibility? Stress doesn't burn any extra calories, and it feels icky. You can handle this!

Personal history, since you asked if it worked for any of us:

MFP's prediction for weight loss calories was waaay off for me (rare, but possible). I figured out during weight loss how much I needed to eat to lose at the pace I targeted (by looking at my own logging data and using arithmetic). When I went to maintenance, I used my history data to estimate maintenance calories. That worked well.

I did choose to gradually increase calories to maintenance. It was a bigger chunk per day at first, I forget exactly what - maybe a couple of hundred calories - because I'd still been losing more than half a pound a week on average. After that, I added 100 daily calories, and watched my scale weight to see what happened. The more times I did that, the longer I needed to wait for a trend to emerge from the confusion of day-to-day water weight shifts. Eventually, I settled into a standard calorie goal.

Partly, I took the gradual approach because I wondered if I could nudge my calorie needs upward if I did (reversing adaptive thermogenesis). Partly, I did it because I know myself well. If I'd added some big chunk of calories all at once, I would've been tempted to add some calorie-dense treat food to my daily routine - not what I wanted in my better moments. By adding gradually, I was more likely to add pleasant but nutritious small tweaks to my routine, instead. That also worked well for me.

That was 7+ years ago. I've stayed in a healthy weight range ever since, and the same jeans size. I've been up and down a few pounds sometimes, more about things like holiday indulgences than because of routine calorie goal stuff. I think I'm less anxious about the whole thing than you sound like from your post, so I'm not motivated to maintain within super-tight limits consistently, but I'm quite certain I could.

How fast have you been losing recently? If it's still pretty fast, like a pound a week, you can afford to add a bigger chunk of daily calories initially. After that, it's fine to add gradually, if that's more comfortable for you. You'd probably continue to lose slowly for a while (I did, and overshot goal weight). Keep in mind that when you add even a small increment of additional calories, you could see a little water weight weirdness on the scale. If you gain more than predicted from the number of calories you added, it's water retention (or extra fiber and whatnot in the digestive tract, on its way to becoming waste). To gain a pound of fat, you need to eat roughly 3500 calories more than true maintenance calories. If you add a couple of hundred calories, and the scale goes up a pound in the next day or two, it can't be fat, it has to be water/waste. It'll level out.

You can do this. In fact, you must do this: It won't be healthy to keep losing-losing-losing, right? It'll be OK. Eat more, monitor, adjust - it'll work out.