How long should i wait before going back to skydiving after a breast reduction?

You should be just fine skydiving 6 weeks after  a breast reduction if you didn't have any post-operative healing complications. 

I tell my patients that they can resume normal activities 6 weeks after a breast reduction- at that time the tissues have regained 70% of the final strength and are strong enough to withstand most forces.  But most patients tend to wait 6 months to get a mammogram because the breasts may still be a little tender.  A parachute popping open may be a lot of force and you may feel more comfortable waiting longer.  But the incisions should usually be strong enough by 6 weeks.

Asking questions so you can find other opinions is self-serving in  my opinion as you are only looking for someone to back up your desires to resume activities sooner.  Why the resistance to following your surgeon's advice?  If you resume skydiving before 6 weeks, you are doing it at your own risk of some problem arises from it.  And if its topless skydiving, even longer because its amazing what distortion you get from the wind.