It will be tough, but if you have a good plan, you should still be able to get most things on your list accomplished.
We went in April (week after Easter) and my BIL who's a CM got us in each morning. We were able to book fastpasses once in the park each day (for that day only), but the selections were kinda thin. Given that you are going in a busier time, yours will probably be even less.
My advice would be:
1. arrive EARLY to get to the front of the lines for rope drop at each park
2. research the top priority rides & characters for each park and plan accordingly (do the most popular things immediately after arriving at the park before the crowds have time to build)
3. consider staying LATE - the crowds thin out after the nightly fireworks (and some even before then), so if there's an opportunity to do things after (or even during) the shows, take advantage of it and squeeze in things you might've otherwise missed.
It can be done, but it'll take some patience, planning and understanding that there will be a good deal of waiting in lines.
Have fun!