(((((desi)))))
you've already been given some excellent advice. as i was reading through your thread i was making some notes that i'd like to share with you...
1. appy stimulant: not all cats do well on mirtz. ask the vet for cypro (cyproheptadine). tawny may do a lot better with an alternative such as cypro (alex does). she gets 1/4 of a 4mg tablet every 12 hours as needed, but ask your vet about an appropriate dose for tawny.
2. sub-q fluids: a "must" for helping to flush ketones out of kitty's system. until you can give her squids, syringing as much water into her as possible every hour or two is better than nothing. i can usually get about 25ml water into alex before she starts fighting me. it's a poor substitute, but like i said, better than nothing.
3. food: give her anything she'll eat as often as humanly possible. she has to eat.
5. insulin: now's not the time to cut back on insulin. however, as you know... it's tricky when a cat isn't eating.
here's a quote from jojo regarding insulin/ketones,
"i would rather feed the cat total HC and get more insulin in if the cat is in a real danger zone cause of history. remember w/ ketones the BG number doesn't matter, the amount of insulin getting into cat does. so if you have to food manipulate, so be it. ketones and BG number have no connection, a cat can throw them w/ BG of 120 or 520, the only reason BG and ketoens seem to have connection is that a BG of 520 usually sends plain signal that not enough insulin getting into cat while the 120 doesn't let you know. (a diabetic cat can be in 'full blown DKA' and have BG of 120 from not eating and puking and being septic, most won't but ECID and it can happen)."
i also encourage you to seek help from those who have experience with R. here's a ss which shows an example of using a basal insulin along with R plus the use of food to fight off ketones successfully:
Grace's SS.
6. actigall (ursodiol): if tawny needs it... give it to her. don't skip a dose. i know from personal experience that withholding actigall from a kitty when they need it doesn't work. when we (my vet and i) attempted to wean alex off of it before she was ready she relapsed (more than once). to this day she requires a maintenance dose administered every other day.
7. denamarin: this supplement should be given on an empty stomach at least one hour before eating. it's my understanding that the effects of denamarin diminish greatly when given with food.
8. pepcid: if she needs pepcid, offering 1/4 of a 10mg tablet of pepcid AC 30 minutes before a meal (twice a day) will help.
9. if she's showing purple on urine strips... she should be hospitalized. contact DCIN to find out if there is any assistance available to you. DCIN was aware of your financial circumstances when you adopted tawny.
10. antibiotics: i haven't been around enough to know why tawny was given an ab. however, one thing i do know is if an ab is needed... give it to her. the recipe for ketones is insufficient insulin + poor appetite + infection or certain other systemic stresses.
i know you're aware of the reasons i haven't been able to be around much lately. i wish i could be, but i can't.

hopefully, tawny is doing better today. i'll try to check back later for your update.
sending love and tons of snowflakes and healing vines...