Welcome, Lindy,
You may not get any replies or takers for hiking partners, but you will not be alone on the trail. The quota for backpackers is 60, and there will be at least 50 going up when you go.
September is a nice time to go -- weather is usually perfect, no mosquitoes.
Steve's not kidding.
I was like you, a Mt Whitney newbie, for my first ascent last year. At first, I thought that it was gonna be a spooky (twas a new moon) midnight start the day of my ascent, all by my lonesome. But I was wrong.
In fact, there was quite a bunch of folks going up...and coming down too. You won't be alone.
Have fun. Be safe.
