Hair loss is probably the number one distressing appearance-related side effect of rapid weight loss (honourable mentions to loose skin, of course).
Most, if not all, of us suffer from it. Some suffer more than others. Like the others above, I want to offer re-assurance that its mostly temporary. Little chicken hairs will start to sprout up and then in a year or two those chicken hairs will be down to your shoulders. Im my case (and some others I have read), it actually came back thicker...but i think this is also due to the fact that my overall health is better than it was before.
BUT, in the meantime, here are few couple tips to get you through this annoying stage (choose what you feel comfortable with...or none at all )
1) cut your hair shorter (i did a pixie cut at 3 months). the carpets of hair accumulating on the floor and catching in the shower drain will appear less. shorter hair theoretically will weigh less, so it will be less likely to pull down flat against your scalp and show larger swatches of said scalp. and when the chicken hairs start coming in they are less noticeable and blend in better with the rest of your shorter hair and not look so thin on the ends.
2) keep your hair clean. greasy hair will flatten and mat against your scalp which will show more of it (BUT don't shampoo too much...and that's for everyone, not just those losing their hair!)
3) I think I see what looks like a braid in your hair in one of the pics above? if you can, maybe save the braids for later as the style will pull on the hair you have and possibly come out at an even faster rate.
4) there are these hair fibre "powders" that you can buy that temporarily camouflages the scalp. its basically hair coloured powder that you sprinkle on your hair to give the appearance of fullness until you wash it out later. Best results on darker hair with enough existing hair for the fibres to adhere too.
5) and for the truly brave, there is SMP (scalp micro pigmentation)..its a process whereby a tech tattoos hundreds (thousands?) of tiny little dots on your scalp to mimic hair follicles and create the illusion of fuller hair. I had this done last year because I have had the same side part in my hair since I was like 8 years old, and as the years have gone by its was noticeably thinner in that section. Full disclosure: it effing hurts. but I'm happy with the results, lol.
6) and lastly, at least for me, vitamins, creams, lotions did nothing to stop or slow down the hair loss. i know lots of folks have sworn by some or all of these methods, so ymmv.
Good Luck, and hang it there! ❤️
P.s. sorry this was so long.