help with my pushoff?!?

[LancerVaulter07]

i'm a sophomore and i jumped 11'6'' this year in a meet
and i did cleared 11'9'' in a practice. i was jumping on a
13'1'' 135 lb rocket pole with pretty good bend. i am 5'7 1/2''
and weigh about 135 pounds (during my season) and this year
i was pretty good at getting my shoulders and head back and
getting verticle but something happens and i can't figure it out
(due to lack of a coach or another knowledged vaulter to tell me)
and i don't get a good pushoff on full vault. yesterday i held
about 8 feet and cleared 9 (just practicing swinging and turnover)
is there anything anyone might be able to think of to help me?
please post...all advice welcome. thanks.

oh, i was also holding about 12'6'' on my pole this year