Ideas to stop 6 month old biting?

She's been biting since she came to us at 12 weeks (she's 6.5 months now) and I have sought out different approaches to stop the biting. I've tried the crying out method, removing myself, I brought her to a positive reinforcement trainer who told me to give her lots of treats when she's calm so she knows to 'keep that mindset' but that didn't work.

I went to another trainer who introduced the prong collar, which has helped a little. In the classes, she is well-behaved, doesn't bite, etc., but as soon as we get home, her excitement spikes out of nowhere and she starts jumping and biting and doesn't seem to mind the correction from the prong then.

It isn't really aggressive biting more like play biting but I would still like to nip this (no pun intended) in the bud so she understands it's not acceptable to put her teeth on anyone even in play.

Any ideas on what approach I can take to stop this?