Okay, Gentoo round 2 has begun officially (my body was acting up, had to make it chill). Good news, my partitions were remembered from the previous session that ended in doom.
I have used fdisk to confirm their labels are intact from this morning. I do need to mount them before the next step, however, as they are currently unmounted.
This is going a lot faster as it enables me to follow instructions at a reasonable clip. Got to the chroot stage a lot sooner, just took about an hour!