I have quoted only part of what you wrote, but I was touched by all of it. I had a period of unexpected poverty years ago and I understand how hard it is to be able to afford the basics that seem to be so very expensive when one has no money. Here are a few things I discovered and I hope they help:

Don't give up on Goodwill (or other thrift stores) just yet. There are certain days that are better to shop than others. Some of the stores here have one day a month where everything is half off. You might see if this is true where you live.

Our thrift stores here do get new donations from stores. I have seen dresses, sweaters, tops, shorts and other items, still with tags. You might ask if this is the case where you live, and see if the clerks know when those donations generally come in.

Youtube has videos on how to cut your own hair. I used one and got good results. I only gave myself a trim, though. You might also check out local beauty schools and see if they offer low cost hair cuts.

My local drugstore often has random beauty products on sale marked way down at the end/beginning of the seasons--I guess to make way for new products by those companies. You might get lucky with that if you are willing to drop into a few drugstores in your area.

I learned to say "I'm on a budget." So many of the people who are working (in the doctor's office, at the store(s), at the hair salon, etc.) are too, that I sometimes get good advice, tips on saving $$ on whatever it is, or leads on low-cost something just by having said that. Once my doctor knew that money was tight, she kept an eye on the cost when she wrote my prescriptions.

If you have a friend in a similar position, you could do each other's hair, too. I had a friend who taught me how to "shop poor" (her expression) and she showed me what to buy and what not to buy at the local dollar store to get maximum effect for my few dollars. I will never buy big name laundry detergent again!