Yours is not uncommon from what I have seen here.
You have to heal, get your mitochondria working, and get more of them, this all involves proper nutrient intake. If you have cut for the whole time you are in keto you have to allow things to fix themselves my thoughts are it this order
A: give you body enough fat to allow it to use it on lower level functions and not budget let it spend like a drunken sailor.
B:give it the building blocks to fix, add or change those problems that may not have been addressed yet via protein(I used a lot of fish in the first few months)
C: allow it to go catabolic once A&B have been taken care of via a fast on the order of 48 hours min. to kick in some of the other processes like mitophagy and autophagy.
D:Add quality muscle after A and B have happened enough to get ahead of the game. When fully fat adapted slow response muscle burns around 300 calories per kilo I believe(don’t quote me) Adding the right lean mass turns you into a fat burning machine.
I would say in your case, assuming no other major metabolic dysfunction I would get to your BMR levels in short order maybe in 2 to 3 days, if they are less than 500 calories away jump up now. Stepping up would probably be better than all once, just in my n=1 world someone maybe able to offer other advice. I would shoot for 1.0 on the protein scale for a while, if you test you can watch the results a little closer than feeling. Red meat and fish, but liver is excellent as well. This would have to be more about how healthy you are than anything else.
Once you get to the BMR level and hold it for a few days, I would say you should feel good, have energy and never be hungry, then in a few days more increase again in fat,(how much I dunno it is 1/2 cup of HWC for me) this will raise it (not the hard number) by your body bleeding away the excess and using it in places like the immune system etc. From there I would fast for a short time, maybe 2-3 days and see how you feel. The key is you need to feel good, and not be hungry, save maybe some salt hunger while fasting. Rinse and repeat all over again. I have normally taken a 3 day break at near my maintain levels, then boost for 3 days. I have not always fasted, when I have they all have been 60 hours or more on this protocol. I am currently boosting right now at day 2 and its working the same.
I have much success with 3 day bursts again that is an n=1. Your TDEE will also play into this so that may be a better number to shoot for if you are really active like me.
So normally(not boosting) I am closer to maintain macro fat levels, I eat to satiety most of the time(the fat macro is not important anymore at my stage), but when I want to boost I add extra, this will make me “full” maybe a little bloated feeling like in the carb burning days about an hour after my first meal. I will do a shake but the how is not important as the timing, trying to get your protein in earlier, and be more fat heavy later so the insulin response is lower. I have my second meal which tends to be fat heavy and minimal protein.
The difference is noticeable after 2 days, and on the 3rd day I am typically really stoked and moving all the time, hot, and loosing some weight or body fat. I have not hat a chance to try more than 3 days in a row yet.
I hope this makes sense I typed this over an hour and had several distractions.
@Capnbob has the calculator link.