Actually, it has been proper. We don't have a mandated structure on here. You opted to not clarify where you two stood on certain principles prior to it beginning (this isn't uncommon). This is still on you two for turning it into this mess.
What you tried doesn't matter. What you decide is what does.
My reasoning would be that yes, potentially multiple spells (up to a capacity dependent on the complexity of the spells being used at the time) could be charged at once, however, there is a maximum amount of energy that can be transferred to them each turn. So charging only one spell benefits you in boosting its strength greater than preparing one spell. So, while either of you could actually prepare multiple spells, you are hedging your bets vs actually fully boosting the strength of a spell. You'd assume both characters, unless otherwise stated, have similar energy outputs per turn.