Congrats on quitting, even for something considered "mild" like caffeine it's not easy. I had the same issue with headaches so I scaled down by mixing increasing ratios of decaf in my coffee grounds over a couple months, starting with just 25% decaf. The gradual reduction in potency was barely noticeable. Once you get to 75% decaf you're basically drinking full decaf already (decaf usually still has like 10% of the normal caffeine content) and I had no ill effects from quitting completely after that. If you subsequently decide to relapse with decaf or half-caf it's also much easier to quit again.