Hi there and welcome to the FDMB. Yes, ditch the vetsulin and get Lantus for your kitty! Lantus and the advice from the gurus here at this site did wonders for my boy and he is now in diabetic remission.
My 10-year-old boy Hendrick was diagnosed last January and I began my journey thinking that the home testing was flat out impossible. And yet, eventually, I got the hang of it --- if I can do it, so can you.
I eventually started making homemade food once a day for the evening meal. I use the pre-mix powder from Food Fur Life, as linked above, and mix it with raw meat (pork loin, chicken breast, chicken thighs, and turkey thighs).
They ABSOLUTELY LOVE IT SO MUCH OMG
I take a lot of pride in making their evening meal by hand and it warms my heart how much they love it.
For home testing, one of the key tips I got was to use a tiny smidge of vaseline, and another was to make sure the ear is nice and warm. We bought a USB-C rechargeable handwarmer from Bezos and it worked great. Other people take an old sock, fill it with rice, and nuke it up in the microwave.
Also, pick a testing spot and always do the home testing there. Give freeze-dried treats whether you have a successful test or a fail. Eventually kitty learns that test time is treat time! Hendrick got to the point where he would go to the "Pokey Spot" as we called and sit there looking at me hopefully! Actually wanting me to test him so he could get a treat. Cats are creatures of habit and so you can condition most cats fairly well with some effort.