I booked what I have for our next trip for Dec 2019, last Dec 2018. Couldn't get all the room categories even then that I wanted. I am still checking often to change my category if it comes available.
Lack of availability in April is not at all surprising at this late date. Getting anything plus with a discount for that time DOES surprise me, however. I would grab one of the available options and keep checking the website to change it if something new becomes available. (BTW: Since you say it has a pirate room available, I suppose that you mean CBR rather than CSR?) In any case, any of the three resorts you mentioned would work for us. We would probably select SSR if we wanted extra space OR POR RR (request oak manor) if the SSR resort 'theme' doesn't appeal right now. CBR pirate rooms have full beds, I believe, and we would rather have queens so it would be our last choice. (Although with the new changes at CBR, we are planning to revisit that resort soon.)
Good luck getting a room that you will love!