Glad to see you again, Nevetharine !
I am no expert in nutrition so will let more experienced people answer your question on metabolism, but wanted to give you a hug re. size and plate size : I feel you, girl!!! I am even shorter than you (1 m 42, 4'8''), and I definitly must watch my portions. This year I have lived a lot with my parents ; it is mostly a blessing , however it makes for a quandary for food, they cook very well (and do include veggies fairly well too), but they do tend to make for larger portions that I should eat, and longer meals (I nearly never have a starter when by myself, for example, and cakes are an exceptional thing...).

So yeah, part of your issue may also simply be your size. Hugs. (and as a pharmacist, though, I will add that hypothyroidism definitly will not help regarding weight, good luck on stabilizing that because it is not an easy thing).

Shortness is definitely an issue. I just supplement Iodine for my thyroid. That seems to help but weight loss is still hard. I'm eating a child's portions... in fact... most kids eat more than me

There are some situations in which the number of cals to have no variation in bodyweight is very low (e.g. it's not possible or is not suggest to cut any cals in the diet),. As a matter of fact, the body is adapted to have few cals and then the TDEE (Total Daily Energy Expenditure) is very low, since your body try to optimize the cals income.
The the idea is to boost up the engine and not to give less gas to it. Thus, there is a phase where the cals are increased (to allow a better management in future meal plan). At the same time, it's needed to increase the consumption of cals and to make powerful your body. This means, that your body increases the TDEE (i.e. the requirement). Tipically, the training is non focused only on cardio, but on strenght.

Then there is a phase, where the cals will be decreased to reach a "normal" situation for the body.

Anyway, the thyroid functions are related to methabolism and then any diet needs more attention.

Muscle is expensive to maintain so lift like and beast and feed it. That will get you some more calories overall but you will probably have to go into a surplus (minor one) to get there.

The couple big things are yes your metabolism will "repair" as in if you feed your body you will gain muscle and more than likely move more in general. Both of those will increase your overall caloric needs. There will also be the minor thing of you body being less lazy overall since you have enough food. I would also recommend exploring what makes up your macros a little if you want, for example I run best on nearly 50% carb and bare minimum fats. I build my general break down by making sure I hit my fat target, then protein (super easy for me, I eat a ton of protein), and then fill in everything else with carbs. This keeps my energy levels high and I fidget a ton. This may not work for you as I know people who are nearly opposite of me that work better that way.

All this being said weight is a numbers game and being shorter you will always have lower numbers. I maintain on 2600-3000 calories a day but I've got you beat out by a foot in height so I wouldn't expect that from you. Could you get up to 2000-2200 a day though? Possible just hit the weights and find out where it takes you.

Side note: I do know a lady who is 5'0" and 45 y/o that eats about 3500 calories a day. It could happen.

I currently have access to 40lbs of adjustable dumbells but I'm not sure how much longer l will. They are an option to sell when it comes down to it.

So, let's assume that I only have access to bodyweight training (Darebee) for building muscle. I know muscle building is mostly about nutrition, but just to make sure, will I be able to build enough muscle to help my metabolism recover with bodyweight only?

Also, nutrition-wise, I can do a surplus, but it's not food great nutrition wise. We are severely budget restricted, but I am able to get protein from legumes and occational animal products. At the very least, I get 40g of protein a day, anything above that is a bonus.

A lot of the surplus calories will come from a mix of complex and simple carbs.

You can!*
Go for Ironborn or XPress, as long as you are able to use DBs, cause it is easier (as in less complex) to build muscles with weights.
... and then change to the other (bodyweight) Darebee strength & tone programs,

Additional bodyweight exercise information you can use for free... on youtube...
FitnessFAQs
Calisthenicmovement
Tom Merrick
School of Calisthenics

* ... at some point additional weights might be mandetory, but for now you should be ok with bodyweight exercises.
... or you improvise with stones, water bottles, sandbags, wooden logs etc.

Hypertrophy is based on failure an the conttrary building strenght is based on a progressive overload and principally one train with a buffer. Obviously, to manage a progression is very easy with weight to lift since they can be measuerd, but also in calisthenic/bodyweight training it is possible. The exercise have a ladder of progression that allows such a thing.

My train is based* on calisthenic and for a lot of time I have worked only with my bodyweight to do push up, dips and pull ups (and their progressions and variations). I can clain that strenght can be build also without any weight.

The links posted by HellYeah are a lot of good stuff



*Now my workout is focused on weighted calisthenic where the same exercise are done with an additional weight, and for legs I use do back squat in my garage (not now, since the it's too cold)

I've started Iron Born today. I'm not as weak as I thought I would be,

I haven't done any strength training in months, but I could do day 1 with 11lb DB's. Some exercises were even too easy on that weight. Happy with that.

I've also added some more food. Unfortunately its mostly carbs, but well that's all we can afford right now.

I'll go through IronBorn and then maybe do it again at a higher level or do Xpress. Maybe a few months (4 or so) from now I'll focus a bit more on weight loss again.