Hi, JP,
In your case, you could use MiniTool Partition Wizard to resize your partition.
Shrink C drive to release some unallocated space, then add the space into other partition which you want. In AddRAM suggestion you'd better set your partition D and E to logical, that's right, but you need not to have your data off, MiniTool Partition WIzard support set primary partition to logical without data loss. Like what AddRAM said, you'd better do the operations under the boot mode.
In my opinion, you'd better upgrade your hard disk to a lager one, your data is too much.