Preconception blood work?

I have an appointment set up with my OBGYN for the first week of March, but I have an appointment with my PCP tomorrow morning for my annual visit and to get a referral for a vascular specialist to look at a varicose vein in my leg. We have been TTC for 4 months, I’m 34 and a little concerned about my progesterone and/or estrogen levels since the past 6 months or so my periods have been very short (2 days max) and I’m not bleeding or clotting, it’s more like a thick dark brown paste. I’m concerned that my lining is not building properly so I want to request some preconception bloodwork. Would my PCP be able to order that while he’s running my normal CBC labs for my annual, or would my OB/GYN order the preconception blood work? If you have had preconception blood work done, who ordered yours?