You have osteoarthritis of your knee. A MRI is not the best indicator, I would strongly recommend a weight bearing X-Ray. If the arthritis is localized in either the inside or outside compartment of your knee then an unloading brace or a simple heel wedge may offer you some relief. Studies have shown that maintaing a strong knee improves function as well as reduces symptoms. Physical Therapy for closed chain exercises would be helpful. However continuing a program at home is necessary. If your synovium is hypertrophic, an arthroscopic total synovectomy with injection of Stem Cells would be indicated. Synvisc injections is a thick lubricant that makes your knee glide better reducing pain and symptoms. Over the counter remedies include ice packs compressed with sirsranrap , Omega 3 fatty acids, glucosamine chondroitin sulfate,and tumaric. Sometimes compound creams applied to the knee can relieve symptoms. A patella brace can reduce symptoms going up & down stairs , getting up from a sitting position or getting in & out of a car.

Most important do not let anyone talk you in for having a partial or total knee replacement. You are way too young. They need to be replaced every 10 -15 years. Each time it gets more difficult and complication rate goes up.

Good luck, you have a lot to do and will notice an improvement