No Sugar, No Flour, IF Questions

I started no sugar, no flour 19 days ago. Overall it’s been great and I’ve lost 11 lbs of the 50 I would like to lose. I started IF 10 days after I began ns, nf and lost a ton more weight doing that. Until 5 days ago. I can’t figure out what is happening. I was dropping weight, it felt like it was falling off. And suddenly I gained 2 lbs and it’s taken me 5 days to get it back down. In my mind I’ve been following the protocol perfectly and wanted to know your thoughts.
I am having my last meal between 6 and 7 each night and starting my first meal of the day between 11 and 12 (lunch). I’m only eating 2 meals (lunch and dinner, no snacking). I’ve struggled with fasting for 20 years (severe hunger, shakiness, terrible tummy upset) and suddenly in the last 8 days it’s been glorious and I haven’t had any issues (presumably because I’m doing no sugar no flour?). I’m not hungry usually – even at 11 or 12 for lunch, but feel like I need to eat. I’m not a coffee drinker so I’m only drinking water in the mornings. I’m getting very full at my 2 meals and am having a difficult time getting enough calories in.
1. Could my body be decreasing my Calories Out because I’m not bringing enough Calories In? My typical day I’m eating about 1000 to 1200 calories. I’m working hard to add fat and not go crazy on the carbs. My carb intake is usually around 60-100 g/day. Fat is typically 35 g/day.
2. I’m drinking 8 oz of store bought (not homemade) Kombucha each day during my eating window. Could that be spiking my insulin too much? Is Kombucha allowed?
3. I’ve just finished reading The Obesity Code (it was fascinating, thanks for the recommendation). When he talks IF, he suggests 24 or 36 hours vs the 16-18 or so I’ve been attempting. Should I try that?
4. OR, is this just a result of my body still trying to get fat adapted? I’m only 19 days in to ns, nf and only 8 days in for IF. Do I just continue with my 16-18 hr fasting window and press on? Will I start to see the weight drop more? Or do I go back to adding in breakfast and wait to start IF until I’ve lost more weight?