oh, that's so frustrating.
Here is a link with other reasons for flower drop besides lack of pollination.
google "tomato" "flowers" "drop" and you'll get lots of other URLs
This link seems to suggest that your day time temp might be a little too high if you don't have the varieties for that weather.
Which varieties are you growing?
I had that drop problem last year, my first season where I live now. This year, I'm spending time had pollinating my flowers, even though I have some bees working the tomatos too. Almost all of my flowers are setting fruit.
I just vibrate the flowers by hand and that seems to do the trick for me.
Please let us know what you figure out.
Do I contradict myself? Very well, then I contradict myself. (whitman)