The starlet was back to doing what she does best this weekend in Miami -- being the life of a party as she DJ'd a set at Wall Lounge, where she was on the turntables for a majority of the night. As you can see ... she doesn't seem fazed in the slightest by her breakup.

It wasn't just her body language either that tells us she might be as happy as ever -- her song selection speaks for itself, too. JT's "Can't Stop the Feeling!" ... "Opus" by Eric Prydz ... "Free" by Ultra Nate ... and an "iconic as f***" song that cuts out before it can play.

Talk about feel-good! She's kinda been on that tip since calling things off with Chris Zylka, having looked in very good spirits lately, sans her pricey hardware.

As they say ... back to business.