Most blanks do not need a lot of added rocker since the blanks are designed with proven curves. Blank selection is very important. If adding more than 3/4" of tail rocker choose a longer blank and cut the excess length from the tail so there is extra foam thickness to shape into. Good shapers plan their shapes first and choose the best blank for the least amount of work.
In this case we'd cut the tail shorter to where you have about 1/2" of tail pod thickness and reshape it a little. Chalk it up to a learning experience, the board will still surf fine and you'll be stoked on it.