[credence huffs out a laugh that is partly relief and some of the tension drains from his shoulders.]

Me neither.

[is a charitable way to put it. his eyes flick from mr. graves' face back to his coffee.]

I don't know where to start. [he'd ask to hold his wand, except he already said he didn't have it. instead he pauses, pursing his lips.] How do you do spells? And--why do you need to make potions if you have them?