Welcome aboard! Elise has covered a lot of info for you already. It is fabulous that you are testing!! Diabetes does definitely have a steep learning curve, and the whole process is a marathon, not a sprint. As others have often said here, your kitty didn't become diabetic over night, so gaining control won't happen over night, either. But between starting insulin AND testing, you are well on your way!
The spreadsheet Elise mentioned will be an incredibly helpful too, for you and for those helping you.
All of this seems overwhelming, but we're here to help you - with both technical and emotional support, so please keep posting questions!!