Lindsey, I am so sorry to hear that poor Lacie is having more problems.
My vet has told me that diabetic cats are more prone to cystitis and she has been through a lot of stress recently, which can't have helped matters. Maybe she just needs a longer course of ABs?
From my own personal experience, I can vouch that having a diabetic cat can be very costly and emotionally draining - especially during the first few months. I was initially fostering Sweep for my local CP, and after he racked up over £2,000 in vets bills in 5 months, they 'pulled the plug' so to speak. However, we negotiated a discount with the vets and began to perform glucose curves at home - emailing/ringing the results to the practice for interpretation and advice on the correct insulin dosage.
If you can get Lacie over this initial ordeal, I believe home monitoring will be the answer to many of your problems:
Firstly, it reduces the stress on the cat
ie no travel, no vets etc.
(and stress can elevate glucose levels)
Secondly, it can be done relatively cheaply.
The glucometer I use only costs £10 to buy, the strips £25 for 60 individual tests, and needles £5 for a box of 100.
(You can also buy 'ketastix' for £6 to test for glucose & ketones in the urine.)
This literally saves £100's on veterinary bills, and if your cat shows any stange symptoms, a quick test can alert you to often remedy the situation before a life-threatening problem arises.
In turn, this also gives you more peace of mind.
I know how shattered and overwhelmed you feel at the moment, but providing a trusted vet thinks Lacie will overcome this, then you can cope with this I'm sure.
(And please don't hesitate to PM me for info - or if you just want a chat.)