I would say you are out for 3-4 months. You have an initial 6 weeks for the fracture to being to ossify. It really wont be at full strength until 12 months or so. Although the fibula is not a weight bearing structure when standing it dows undergo a lot of force when changing direction etc weaving when running. Also to have broken it you should have also suffered ankle ligament damage. But with no pain that is a little weird. Is there any history of brittle bones in your family? Or maybe you are a female rugby player who feels no pain! I know there are many of them

In short it will be a close call but you won't be match hardened by August.

If you have any x-rays please do post them as an attachment