I had a fracture of my right tibia and fibula along with massive damage to the medial ligaments a few years ago. I was 50 at the time. I had also injured them several times while in the Army. While the bones healed up after 3 months, the ligaments did not fare so well. I now say that the only thing holding my right ankle together is "skin" and has limited my ability to play action type sports like football, basketball, etc.
Your injury sounds similar to mine. My advice is to not try to hurry the recovery. You don't want to develop a "failed fusion" of the bones where they never actually grow back together. Additionally, try to get some rehab for your ankle once your cast is off and you are able to ambultate to help restore the proprioception of your ankle joint.
Also, wear some good MX boots when trying to do off-road which I am now doing. My road boots did not provide sufficient support to my ankles for off-roading.
FWIW, I had to keep my foot elevated for almost a month due to the swelling resulting from the ligamentous damage. So don't freak out about your current status.
Hang in there!!!
’00 BMR R1100R: in the past:'07 Suzuki DRZ400S; '95 BMW R1100RS- Stolen
; '88 Suzuki Katana 1100; '78 Suzuki GS1000; '76 Yamaha XS750- while parked, was totalled by an Army Gama Goat; '69 Bridgestone 200 Mach II; '69 Honda Trail 50.