I always measured big last time (don't know yet this time as I haven't been measured- can't be that important?). I don't see the big deal- babies will be lying in different positions. And you have an anterior placenta- surely that pokes out the front and affects measurements? I *think* the measurements can help to determine a potential problem with excessive/not enough fluid? So measuring far ahead and then having a scan may find something? I'm not sure though. I don't buy any of the big-baby stuff though. I had a big baby and I think I'm having another. No biggie. Their skulls are designed to moosh up on the way out and I think they all seem about the same size when birthing. Size is pretty irrelevent really.
Whether you decide to keep up with the fundal measurements or not you can choose not to buy into their "big-baby" scare game. It does NOT mean your baby needs to come out early. It does NOT mean your baby hasn't grown to the right size for you to birth. Your baby is healthy just the way they are. I hope you continue to work through your fears around that- you're doing a great job talking about it