A var weird thing happened.
I put an old disk in there that had also has an old Fedora installation.
The '/' and '/data' (my own) was mounted in THIS disk but the other, like /boot was from the original disk.
No wonder I couldn't get the /dev correct.
I removed all partitions(on the "new" HDD), rebooted and the system was using the correct disk again, after that I could see the partitions changing in /dev when using parted/fdisk.
Haven't tried to remove it, reboot and reattach it when running and see if that worked..... yet