Insurance is another cost you'll have to pay yourself. I don't really know what's available for contractors, but consider health insurance, life insurance, accidental disability insurance, etc. (Dental insurance isn't really a thing. Budget $400 for your two checkups and don't get any cavities.)

Also consider your retirement savings and what you're missing out on from employer 401k matches.

Finally, keep an eye on cost of living and adjust your rate accordingly. The dollar is worth at least 20% less than it was 3 years ago. Charge 20% more.