Sorry, this is posted in the wrong area for responses. Pls. re-post to the 'Discussions' area next door as it were (see top of this page).

These plants don't mind being rootbound, next time, I'd leave it alone until roots start coming out of the bottom of the pot.

Repotting during bloom can kill the blooms -- that MAY be what happened here, repotting while in bloom likely killed the blooms.

What kind of sand did you use & why (pls)?

Sand is NEVER, EVER a good idea. It's likely to block the air spaces in the mix & cause drainage problems in future, pls. don't do that again if you wish to keep your plants healthy.