Am I missing something... she needs a 9-12 to hit. So she's missing ~50% of the time? Or do you mean that the monsters you're using have 9-12 touch AC?
As to damage... at level 7 that electric blast will be doing 4d6+half con, most likely not more than 4 more points of damage. That's an average of just 18 damage a round (assuming she only misses on a one). In contrast, a barbarian with a greataxe aught to be doing something like 1d12+9 (average 15.5) per hit, and that's before accounting for things like rage, power attack, haste, and other effects. Sure, he's hitting less often, but just with power attack he's doing just as much average damage as the kineticist while getting more attacks, which make up for the additional misses. And that still doesn't account for rage. (Note: Assuming 26 con for the kineticist and 22 str for the barbarian; this both exagerates the kineticist's damage and accounts for her being more MAD). A kineticist can do a bit more damage with her physical blasts, but will miss more often because it isn't touch anymore.
Another way to think about this, the kineticist's damage is the same as a rogues sneak attack (4d6). The Magus and a full arcane caster can also blow this number out of the water; fewer times per day, but honestly how often does that really come up? Almost never in my experience; if the arcane type is out of offensive spells then other people are probably running out of dailies too.
A few tips that can make him feel less OP: Offer lots of cover and terrain that breaks up line of site. Offer multiple weak types to suck up attacks from everyone. Pay attention to her action economy and make sure she's using burn correctly. See if the other people are using their builds effectively.