Avulsion fracture 5th metatarsal

Comparing xray photos from 3 days - 3 weeks and 6 weeks after avulsion fracture, very little healing seems to be taken place and there is a 3mm gap between the bones.
Xray at 3 weeks
Xray at 6 weeks
Xray at 3 weeks
Xray at 6 weeks

I did not religiously wear the boot except after seeing the Dr. at 3 weeks, I then wore the boot from weeks 3 to 6. He then put me in a Wraptor ankle brace. The pain has been minimal and I am walking normally. However, I am an elite masters sprinter for my age - 52 and wish to return to competition. How can this gap in the bones heal if I am walking on it all the time and how long should it take? I was told at least 6 more weeks but that seems optimistic. I can do heal raises with amost no pain and sometimes run up stairs without thinking about it with no pain. I want to return to running asap. Am I hurting it by biking, doing rowing machine? Should this be screwed if not healed after 12 weeks total? Could this become chronic where this could be rebroken? How long before I can expect to return to the track. I am a 400m sprinter.