Flare is a freestyle board. It comes with a small fin because theyre made to slide backwards/sideways etc a big fin doesn't help with that.
most freestylers i know cut down the ridiculously small fin because its too big.
if you intend to try freestyle later keep the the 22, and get a bigger fin for the meantime. For a 6+m something around a 34 should work. Keep in mind that the flare is a freestyle board though, so not orientated to cruising around on. Probably acceptable to ride around on if the intention is to freestyle later. Enjoy the broken ankles