Typically we suggest people try an insulin for six months before switching. Having said that, I see you have passed the six month mark. Some cats are less bouncy on Levemir, but it's ECID of course. Levemir has a later onset and nadir which doesn't always work for everyone. Average onset +4 and nadir +9. My Neko on Lev was later than those and it worked great in my schedule. I think the remission rates are similar to Lantus. For me the worst part of the switch was feeling a bit like a newbie again as Neko had to learn how to work the new insulin and I had to learn how she worked it. But she was flatter which gave me longer stretches of sleep at night.
When I had mentioned pens before, I wasn't talking about the pen as a delivery system with the pen needles. You are right, you can't get the smaller doses with them. But you can take the top off the pen and use it like a mini vial. There is a picture in the Sticky Note on Syringe and Insulin Info.
Good luck with the vet appointment.
