How many of these prenatal appts are you having?
I only met with my doula once back in March and we went over a loose birth plan, what to do when I go into labour, placenta encapsulation, and a few other things I can't remember right now.
Since then I have texted her for a few questions that weren't big things and didn't need a call to the midwife. we do touch base after appts and if I have any random questions. sometimes if i'm reading i'll ask her a quick question and get her thoughts. i know i've asked about taking care of an uncircumsised penis because she's the only person i know who didn't circ her son and we aren't either so she's my go to lady on that. i've been having more BH this time and I didn't know how to handle them (seriously I was shopping and thought oh shit what is going on?) and she'll give advice on that kind of stuff.
We are going to meet again in August and at that meeting I will have my full birth plan ready, lotus birth information ready, her final payment, and we will set a few things in stone so to speak. At this point she's pretty hands off but she's available for texts or phone calls.
If you are having classes with her, maybe just right up your questions and if she answers them in them in the class, cross em off and if she doesn't maybe ask during class or afterwards. Or you could always send her your questions and see if it's stuff shes covers in her class?
If anything I would definintely talk about birth plans. Are you homebirthing or hospital/birth center? Are you going to do vaccines? Are you going to breastfeed? What about the various newborn procedures and where you stand with them? Are you circ'ing or not? We are birthing in the hospital and going to deny most of the newborn procedures, so yes my midwife knows this but I also told my doula so that if I can't speak up and my husband can't either my doula can tell the nurses/staff what our plan is. We also turn our birth plan into the L&D but sometimes communication and wishes can be lost so it's good to have that one person there who can speak up if you are unable. Also doulas general help get nursing started, so if you have any questions about that, like what kind of pump she recommends or what to do if you have inverted nipples. Stuff like that you can find in a book but sometimes it's nice to talk to a person and get even more information, even if it is just ancedotal.
Some doulas do postpartum work so that would be something to ask about and then if she does it, what exactly does she do? I'd ask about that. Doulas are also good resources for "mommy & me" type things in the area, so if that's something you are interested in doing you could ask if she knows any programs.
These are just things I've come across and thought of with my own doula so if some things don't pertain to you just ignore it!