Happy New Year Paula!
I think there are bonuses to February and April breaks. April will bring a little warmer weather but it may also bring more people and higher wait times. Typically crowd levels in February are lower except during the Princess Half Marathon Weekend and President's Day Weekend so take that into consideration if your break falls during those times. If your April break falls around Easter (which will be Sunday, April 5, 2015), you can expect the crowd levels to be much higher than in February.
I have a son with several types of special needs so I completely understand your situation. Disney is committed to assisting Guests with all types of special needs including those with
Cognitive Disabilities. They have put together
A Resource for Guests with Cognitive Disabilities including Autism Spectrum Disorder (ASD) which you can find on the link shown above. This will give you some information that may help you during your trip.
If your son is not able to wait in a regular queue, you should visit Guest Relations in the first theme park of your visit to request a Disability Access Service (DAS) Card. I'm limited in space but answered a question for a Guest with more
details of how the DAS works that you may find helpful. Here is a list of
Frequently Asked Questions about the DAS.
We use the wait time to take a restroom break, eat (which takes my son longer) or just give him a break in a quiet corner in the park.
Please feel free to visit again with any other questions. We're hEAR for you!
Wishing you minnie magical memories :-) Allison V.