I always run my Autos 20/4 from seed to harvest, to reiterate what others said you don't need to change to 12/12 and in fact it will be detrimental to the final product.
20/4 is recommended . Some will argue for 24/0 (I like to think they still like to rest as well - interesting things happen to cannabis at night, be it photos or autos) and 18/6 can be run if energy saving is an issue.
I'd recommend more light next time. One 125w is enough to start a seedling but you'll want to heavily increase that during veg and bloom.
Good luck and hopefully she gives you some goodies :smoking: