http://iscoresports.com/

Is there a way to add innings to the beginning of game that I missed?

No.

Say you got to the field at top of third inning. You can use MISC > ADJUST SCORE to set the score, inning and batter at plate and start your pitch by pitch scoring from there . But You can not then go back later insert pitch by pitch scoring of the missed first two innings.
To include those missed innings, You would just rescore the whole game as a new game

Thanks. Not what I wanted to hear, but good information for the future.