Ok, I'm a single mom since day 1, and my dd and I have gone to WDW maybe 15 times. So, I"m not really sure what there is to be afraid of, lol. Of course, I only have one, and generally the only tantrums are thrown by me.
So, start voicing your concerns, and we"ll help you over them.
Here's some ideas:
Riding rides that are two-seaters?? Have you dd's sit together, and enjoy watching them!
Safety? Fifteen trips, never felt 'not safe'. Seriously, take a deep breath and don't think about it.
Money? You dd's are a great age. I usually give me daughter a certain amount of $ per day. And I agree to buy her one thing (I learned to set a $ limit on that, too!).
Meals? I've had my best times with my dd at disney, and yes, at meals. Just eat where you think everyone will find something to like.
I've found that Disney has become such a special place to us, because it's one of the only places that mom is playful all the time. I know that when my dd says she misses WDW, she's really needing some carefree mom time. And that's tough to come by here, there's always something that needs to be done, etc.
Don't think, just book it and GO! You and your dd's will have the time of your life!!!