If still slowly gaining, then you are probably eating over your TDEE.

If you saw initial bigger weight gain, and it's diminished in amount, but still some gain, your metabolism sounds like it's done coming up, and you just have TDEE calculated wrong.

Because, actually, with the gain would have been an increase in TDEE, yet the gaining remains.

In last 3 weeks, how much have you eaten on avg daily, and what has been the total gain in that 3 wks?

Ah bummer, so can't calculate what the real TDEE might be, based on the gains.

But if you were still undereating, and your body felt too much stress, your metabolism would have just raised enough and you'd be sitting at no loss or gain.

So unless it's still coming up, it sounds like you reached TDEE and more. Might want to weigh-in, and give it another week and weigh-in.

Morning after rest day, no high sodium meals on rest day.

What I found when I did my first reset was went I did a couple small increases I didn't really gain much BUT when I did the final 600 cal jump to TDEE I gained like crazy! In the 6-7 weeks I finished before giving up I gained 15 to 20 pounds and was busting out of my pants.

I had a huge deficit to make up between what I was eating originally and TDEE (about 1000 calories!). I think my body was just completely overwhelmed with the big jump in calories regardless of whether the goal was true TDEE or not. My body couldn't switch gears that fast and just packed on every calorie it got above what it was use to consuming. It sounds like you may have taken on a big jump as well; I have a feeling it takes the body substantially longer to heal the metabolism and slide the TDEE up to where it needs to be optimally when the jump is big.

I'm just about to start my second reset about a year into this process. My body has slowly been asking for more calories itself after I righted myself following the first failed reset. Slow and steady seems to be best for me. I've stayed right at that 20 lb gain although I'm only 150 cals under TDEE now.

If the gain is still coming too quick maybe consider backing off a bit on the calories, holding there and waiting until the weight stabilizes. If it immediately drops add 100 calories quickly since you know you have already reset above that calorie goal. If it is stable that is probably how far your metabolism has slid up. Hang out there until you feel ready and then add 100-200 calories until you feel stable again. Repeat until you hit 2300 then see if you gain there. If not try for another jump just to see if 2300 is really your max or if it is higher. No sense in leaving calories on the table

This process is so stressful at times; I know where you are and it is hard because most people are not going to understand. "You're trying to lose weight by gaining it? Are you insane?" Etc... I absolutely did stumble. Hard. On my face. No shame. You can do this. But if you need a break to regroup no shame in that either. Do what works for you. As long as you don't drop your calories into the floor you should maintain whatever gains you've made so far.

Good luck!