Hi GabbyGrixti123 - welcome to the support group -
in regards to the MRI showing nerve damage - it depends - the MRI must be done with and without contrast dye - sometimes it does show a pinched nerve and sometimes they can be hidden behind a disc or bone and won't be visible. I don't know what the medical care is in England but I don't believe you are too young for an MRI - Here in the USA, MRI's CT Scans etc are given to children to help with diagnosis, etc. Hopefully the Orthopedic will agree and give you one.
there is a 2 part test that may also help - EMG with Nerve Conduction Test - this may be able to tell where the nerve is and if there is any damage to it. Again, this test may or may not show this.
Another test would be a Myelogram test.
You are so very young to have such a dramatic and painful situation. I trust that you do have good doctors around. what we try to suggest is that you see either a Orthopedic Spine Specialist or Neurosurgeon Spine Specialist. they are the only ones that can accurately read MRI/CT Scan etc., results. Hopefully they will be able to let you and your parents know what is going on and give a accurate diagnosis and let you know what type of treatment options are available.
Please keep us posted what you find out - prayers are with you~~