Stoddert and PPA are not good futsal options unless you just want to throw a team together and play with no training. Your not going to find "competitive" futsal in something like that.
I agree about Alexandria - they are your best option for futsal and should be your first choice. Only problem is you may have missed tryouts for the Futsal ID program. I know for my child's age group there are no more tryouts so you should contact them ASAP!
http://www.alexandria-soccer.org/futsal-id-program
There is also dc hyper futsal, it's a smaller program though and might not have open spots-
http://hyperfutsal.com/
A few other options that are farther away but these all have good futsal coaches and might still be taking players.
Puma Elite (FCV) -
https://www.pumaelite.com/page/show/3351971--futsal-academy
VA United -
http://www.vaunitedfc.com/academy/fees/
Premier futsal academy -
https://www.pfava.org/