Hmm. Let me see if I can put you at ease.
MM is less busy than the rest of the day. That is true all year long. Sure, MM might be more busy during Spring Break than during the off-season, but it is still well worth your time to take advantage of it.
I still think you should be able to fit in your Fantasyland list in two hours, but if it goes a bit longer, you have four days at
Disneyland, which is great! I know we tend to get really specific on these boards and that we can probably intimidate those people that have never been before, but I have full confidence that you're going to be able to do all you want to do