Thank you so much for your help!
Thanks for using the forum. I am happy to address your questions, and my answer will be based on the information you provided here. Please make sure you recognize that this forum is for educational purposes only, and it does not substitute for a formal office visit with your doctor.
Without the ability to examine you and obtain a history and review your imaging, I can not tell you what the exact cause of your symptoms is. However I will try to provide you with some useful information.
The cervical spine is the part of the spine around the neck area; the thoracic spine from shoulder area to mid back, the lumbar area down the lower back. It sounds like there are no abnormalities in the cervical spine, neither in the spinal cord or spinal column. It sounds like in the thoracic cord, between the 3rd and 4th thoracic level, there is bulging disc. It sounds like it doesn't compress on the cord or on the nerves as they exit the spine.
There is a material that cushions the space occurring between the vertebra (bones of the spine). This material may sort of be squished out from in between the two bones; this is called a herniated or bulging disc. Buldging discs occur with age, but can occur in younger people, particularly athletes or people involved in heavy lifting or other physical activity. The level of your disc, at the T3-T4 level, would be unlikely to explain the numbness in your arms, since it is lower than where the nerves come off the spine to go to the arms. Hyperreflexia can sometimes happen in otherwise healthy people, particularly young women, and would need to be taken in the context of other abnormalities on exam or other symptoms. Other potential causes of numbness in the arms is neuropathy, which is less likely if the reflexes are hyper, but in general are one cause of limb numbness.
With time, the amount of disk that has herniated shrinks and with time resolves completely in most people. Many patients don't have symptoms from a disc at all, and it is just an incidental finding, done to look for other problems. Other patients have mild back pain or shooting pain down a limb, with the severe pain resolving over 1-2 weeks in most. For some patients the pain is severe, or in a minority of patients, surgery needs to be done. This often is the case when the herniated disc is pressing on the spinal cord itself, or on nerves, which it does not sound like is the case in you. Symptoms suggesting the need for urgent surgery includes muscle weakness, loss of bowel or bladder control, loss of sensation.
It would be best for you to discuss the severity and implications of your MRI findings and how they relate to your symptoms, as well as therapy, if necessary, and other potential causes of your extremity numbness, with your physicians.
Thank you for this opportunity to answer your questions, I hope you find the information I have provided useful, good luck.