$110K as a CTO does seem low to me. Do you mind if I ask where you live?
The salaries in this spreadsheet seem incredibly high for one year of experience.
I started as a Senior Software Engineer and kept getting promoted but not getting any higher pay. As a Senior Software Engineer in 2013 it was great pay. CTO in 2017... not so much.
For various reasons I'm eating the lower pay though. It's rough but I'm ok with it for now.
Do you attend any CTO meetups in the area?
For your retirement account alone you need to get a better job with something at least approaching a market rate salary.