dist = ProbabilityDistribution[{"CDF",
   Exp[-a Exp[-x b] - c Exp[-x d]]}, {x, 0, Infinity},
  Assumptions -> {{0 < a < 10}, {0 < b < 1}, {0 < c < 10}, {0 < d <
      1}}]
res = FindDistributionParameters[data,
  dist, {{a, 3.8}, {b, 0.006}, {c, 0.08}, {d, 0.0002}}]

Plot[{Func[x], bands90[x]}, {x, 0, 3000}, Filling -> {2 -> {1}}]