ISSUE #1 - Barring unpaid overtime, what are their expectations? You're working 37.5 hours per week (7.5 × 5), which is less than the "standard" 40 (though you're still considered full-time for the sake of benefits, etc.). It's unclear whether your 7.5 hour figure includes "non-productive time" (e.g., lunch, breaks, etc.).

ISSUE #2 - Quantitatively, your numbers may be hyperbole, but they don't bear out your claims. Your co-workers have 3x as many fixes as you, but they only work 2.6x as much as you (assuming 14 hours / day × 7 days / week). By these numbers, they are 15% more effective than you are. (And they're harder workers.)

Fundamentally there's a culture mismatch. You think you have differentiating skills—they don't agree. You think you are more efficient—either they don't agree or that's not their metric. You want to work a 40 hour week—they want people who will kill themselves.

There are a couple options (e.g., going hourly), but I don't think they're realistic given the context. After all, your effective hourly rate is way higher than someone who takes home the same salary but works twice as much. So I agree with the other commentators: find an opportunity that's a better fit for you.