Welcome to ATP!
I don't know about your tomatoes: I couldn't live much farther away from you without leaving the contiguous 48 states!
Most tomatoes will pollinate themselves if you shake, tap or vibrate the branches. You might try that to rule out "lack of pollinating insects" as the problem. But if humidity or heat is killing the pollen, shaking the blooms won't help.
That's why most tomato varieties will be 80-98% self-pollinated even if you grow them side-by-side with other varieties. (Having lots of aggressive insect pollinators would increase the rate of cross-pollination).
