New member, new diabetic cat, seeking advice

Hello, new here!! I just have to say how happy I am to have found this site and thank you for all the available information!
Also I wasn't sure where to post to so I posted here and the main page I think.

My cat Luna (9yr female) was just diagnosed with diabetes in early March. Originally she had bladder stone removal in Sept of last year and after was prescribed Royal Canin SO dry kibble. After a few months of being on this food I noticed her water intake was huge which I knew the food was suppose to do that but then she would urinate in such large quantities to a point it became concerning which led me to her diagnoses of diabetes. But I thought it odd the coincidence and started to question if possibly the prescribed food could have been causing this. I asked the vet this and they said it wasn't possible but I truly believe the opposite of this and after reading here I think my suspicions have been confirmed.

The vet has prescribed her Caninsulin and Hills M/D pate along with continuing to give her some Urinary SO dry kibble and I have had her on this since March 12th. Originally she was prescribed 1 unit of insulin in am and pm but it wasn't bringing her BG numbers down enough so after 2 weeks and after a curve, the vet said to give her 2 unit in am and 1 unit in pm.

After doing my own research and from the help of my Aunt whos cat is also diabetic, she told me that Fancy Feast pate is low enough in carbs and a much better price.

So since April 5th I've had her on Fancy Feast pate and am no longer giving her Urinary SO. Unfortunately everywhere in my area is out of stock of Dr. elseys clean protein dry kibble, so she is strictly on 1 can fancy feast in morning and night with a bit of added water in dish (given 30min before insulin injection). I also give her a bit of left over wet food during peak time now as I have noticed her numbers have significantly dropped and continue to stay low since putting on fancy feast.

I test her blood at home before every feeding as well as sometimes during peak. I've noticed her numbers are improving big time but I was concerned its too low with the dose I'm giving her. I've read on here that I should also lower her insulin dose when switching her to a low carb diet and so this morning before her first injection her reading was at 12.9mmol/L which is the lowest I've ever seen it in the am usually its between 20mmol/L and 29mmol/L.
30 min after her feeding I tested her again and she was at 22.6mmol/L and so I gave her a dose of 1.5 units instead of 2 units.

Sorry for such the long message but basically my questions is do you think what I am doing is alright? Should I lower her dose to 1.5 units or maybe even more?

Another thing, before switching her over to fancy feast, I was looking into the insulin. I noticed with Caninsulin her numbers would drop fast but only for a few hours and then steadily climb to such high numbers and I thought that can't be best for her. I researched it was a fast acting of sorts and long lasting insulin like Lantus is much better for cats. And also possibly a better chance of remission with insulin like Lantus. I've talked to my vet about it but they only have experience with Caninsulin and refuse to prescribe me Lantus.
Her numbers seem to be getting better now since being on fancy feast, and where as before her BG numbers would climb after peak back to the 20mmol/L range by pm cycle but they are sometimes staying relatively low now (around 10mmol to 16mmol) but sometimes they are back at 26/27 range again.

Do you think its worth me switching to Lantus or should I just continue her on Caninsulin?
Again sorry for the long message and appreciate any insights!
- lisa & luna