What you can do is, even with Disk Management, convert that "unallocated" space just to the right of the C: to a:
do not, I repeat, do not convert to a logical drive.
After doing that, you can move your data from the "storage" drive, to the new primary partition.
Folllowing that, then delete the "storage" drive,
After that, post a new picture of disk management screen.
Cpmbining the remaining space and/or extending the new "storage" dirve will be easy.