Help recovering hard drive image

I've been working at this for about a week now to no avail so if anyone can help me I would be so, so thankful. Here's what happened:

I get a lot of software through my academic institution, which means that I give it to IT and they load all their stuff. This means that when stuff breaks, like my 2013 MBP Retina did last week (screen broke), I also have to use them as primary tech support. So I made a time machine backup, and when they gave me back the fixed computer I restored from the backup using the data migration. But this time I noticed something weird:

Basically in Disk Utility my "Macintosh HD" partition was listed as a sub-partition of "disk0s2" which itself was a partition of the internal solid state drive. I don't know if this is even possible but that's what was showing, so if I used "diskutil list" in terminal, my actual OS X hard drive was given the path /dev/disk0s2s1 . I thought it was odd but didn't think much of it but then when I tried creating a bootable capitan external hard-drive, the computer stopped being able to boot. Basically when I used diskutil in from Recovery, it now didn't list my Macintosh HD partition at all, it now only had this:

#: TYPE NAME SIZE IDENTIFIER

0: GUID_partition_scheme *500.3 GB disk2

1: EFI EFI 209.7 MB disk2s1

2: 46860E2C-2310-4F96-99F6-616D0B4CB55D 499.4 GB disk2s2

3: Apple_Boot Boot OSX 134.2 MB disk2s3

I had to return the external hard drive I used so I no longer have the time machine backup. I needed the computer to work and work soon so I eventually had to wipe the disk and reinstall the OS. Before doing that I made a disk image of the overall hard drive, which I now have saved on another external hard drive. When I try to mount the image, I run into issues with the filesystem. Using debug in Disk Utility I can reveal all hidden partitions so I now see disk2s2 as a partition but can't mount it because there is no recognized filesystem. I have tried using gdisk and testdisk to recover the partition but I don't know how to make it work.

My hypothesis is this: because of that strange configuration of partitions that I mentioned in the beginning, the "Macintosh HD" partition I want is offset somehow within disk2s2. I'm honestly at a loss of what to do now because I haven't found anyone in a similar situation with the original redundant partition problem.

Please, please, please let me know if anyone has any ideas on what I should do

Code:

$ DISKUTIL info /dev/disk2
   Device Identifier:        disk2
   Device Node:              /dev/disk2
   Part of Whole:            disk2
   Device / Media Name:      Apple UDIF read-only compressed (zlib) Media

   Volume Name:              Not applicable (no file system)

   Mounted:                  Not applicable (no file system)

   File System:              None

   Content (IOContent):      GUID_partition_scheme
   OS Can Be Installed:      No
   Media Type:               Generic
   Protocol:                 Disk Image
   SMART Status:             Not Supported

   Total Size:               500.3 GB (500277790720 Bytes) (exactly 977105060 512-Byte-Units)
   Volume Free Space:        Not applicable (no file system)
   Device Block Size:        512 Bytes

   Read-Only Media:          Yes
   Read-Only Volume:         Not applicable (no file system)
   Ejectable:                Yes

   Whole:                    Yes
   Internal:                 No
   OS 9 Drivers:             No
   Low Level Format:         Not supported

$ diskutil info /dev/disk2s2
   Device Identifier:        disk2s2
   Device Node:              /dev/disk2s2
   Part of Whole:            disk2
   Device / Media Name:      Hard Drive

   Volume Name:              Not applicable (no file system)

   Mounted:                  Not applicable (no file system)

   File System:              None

   Partition Type:           46860E2C-2310-4F96-99F6-616D0B4CB55D
   OS Can Be Installed:      No
   Media Type:               Generic
   Protocol:                 Disk Image
   SMART Status:             Not Supported

   Total Size:               499.4 GB (499417796608 Bytes) (exactly 975425384 512-Byte-Units)
   Volume Free Space:        Not applicable (no file system)
   Device Block Size:        512 Bytes

   Read-Only Media:          Yes
   Read-Only Volume:         Not applicable (no file system)
   Ejectable:                Yes

   Whole:                    No
   Internal:                 No

 

I know haha, the disk is wiped - had to return it to my friend