Not sure if helpful, but ...
My Jaheira is EK 6/Druid 4
and I have what I should at ESL 6:
4 first level, 3 second level and 3 third level spell slots
Yeah, I cheated
and took 6 levels of EK to have the indisputable 2 ESL (and the 2nd Fighter Feat).
She doesn't have access to 3rd levls spells, so she upcasts those she knows
