Hey Jelly
For me, I very very slowly increased my calories from 1400-1600 to 1800-2000 over a period of a couple of months. Everything else stayed exactly the same: eating whole foods, food journaling, weighing myself every week. I also added back in a few foods that I had completely given up while losing weight: the occasional glass of red wine, peanut butter, the occasional dessert treat in a restaurant.
I won't lie, it was SCARY to eat more, I had regained weight so many times in the past, I was terrified I would get heavy again. The additional calories per day are just more of the healthy foods I was eating. Instead of having to pick either a yogurt or a handful of almonds, I could have both. The extra calories felt so indulgent and decadent, I could have slices of avocado on a turkey sandwich, I could have natural peanut butter on Kashi waffles for breakfast!
And of course, I didn't gain any weight back. I wasn't heavy because I ate 1800 calories of whole foods a day, I had been a heavy person because I ate an estimated average of 3000 calories of junk every day.
I like to maintain my weight below 130. I weigh every week, if the scale says 127-129, I eat my maintenance calories. If (rarely) the scale says 131, I shift back into weight loss mode (1400-1600 calories a day) until I'm back under 130. 131 is my "red line, danger danger" mode. Accountability in this way is KEY for me.
In my opinion, maintenance should look just like losing weight, except you get to add extra calories to your day. Only you can figure out the magic number for you
Just go slowly, trust yourself and your new healthy life style, and don't forget any of the good habits that got you here!!!