Hi there, and welcome to Purrs.
Sorry you've found us under such distressing circumstances.
When we had Paddy, who was a 20 year old cat with hyperthyroidism and a heart murmur, and who had suffered from a stroke previously. He would often bring up hairballs, and sometimes just pink tinged bile. Our vet used to give him an injection (am sorry but I dont recall what it was) and it would generally help with the sickness element. I know Paddy was permanently hungry in his last year, and we'd free feed him, but often he wanted to be fed by hand.
I would have a chat to your vet when the blood results come back, as it does sound like she may be dehydrated - again, cats with hyperthyroidism have a tendency to be thirsty more than usual, and the constipation could well be a side effect of that. Try not to worry in the meantime.
Sending warmest thoughts for your little tortie lady.